6066 (1960-1966) GMC Truck Club Bitcoin now accepted here! 
Pay Dues
Pay Dues or become a Site Supporter
 



Go Back   6066 (1960-1966) GMC Truck Club > 6066 GMC Truck Club Forum > Transmissions and Rear Ends


Transmissions and Rear Ends Three on the tree or four in the floor? Shift it all here.

Reply
 
Thread Tools
  #31  
Old July 26th, 2013, 01:32 AM
tatastruck tatastruck is offline
Member
 
Join Date: Jan 2013
Location: San Pablo, CA
Truck: 66 Longbed
Posts: 32
Rep Power: 77
tatastruck is on a distinguished road
Default Re: 3 on the tree

[QUOTE=raycow;49507]If you get an SM420 transmission (used 67 and earlier) it will bolt to your present bellhousing with no modifications needed. You will need to replace the driveshaft, and, of course, cut a hole for the shift tower.

If you get an SM465 (used 68-up), you will also need to have the bellhousing center hole bored out to approximately 5.125" to accept the front bearing retainer. This is a job any machine shop should be able to do.

Ray

Do I need a new clutch or tailshaft? Are the splines the same?
Reply With Quote
  #32  
Old July 26th, 2013, 02:32 AM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 101
raycow is on a distinguished road
Default Re: 3 on the tree

Quote:
Originally Posted by tatastruck View Post
Do I need a new clutch or tailshaft? Are the splines the same?
You won't need to do anything to your stock clutch. The input shaft length, splines, and pilot are the same as on the 3 speed.

Not sure what you mean by tailshaft. If you are talking about the transmission output shaft, you won't need to do anything to that. It should have a flange or yoke on it that the front U-joint bolts to. You WILL need to replace the driveshaft, though. The 3 speed and 4 speed driveshafts are entirely different.

Ray
Reply With Quote
  #33  
Old July 26th, 2013, 02:42 AM
David R Leifheit's Avatar
David R Leifheit David R Leifheit is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, Oregon
Truck: 1960-1966 1000-4000 series
Age: 62
Posts: 281
Rep Power: 165
David R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the rough
Default Re: 3 on the tree

Quote:
Originally Posted by raycow View Post
Addition of the camper changes things somewhat.

If you have a long SM318 now, the most you will have to do is change the yoke. With a "short" SM318 (about 16"), you will need to shorten your driveshaft.

Ray
Since the transmission is -shorter- wouldn't he have to lengthen the driveshaft?
__________________
--
- David R Leifheit
in Dallas, Oregon
mailto:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

(2) 1961 1500
1962 1000
1963 2500
1963 4000
1964 2500
Reply With Quote
  #34  
Old July 26th, 2013, 02:46 AM
David R Leifheit's Avatar
David R Leifheit David R Leifheit is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, Oregon
Truck: 1960-1966 1000-4000 series
Age: 62
Posts: 281
Rep Power: 165
David R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the rough
Default Re: 3 on the tree

Quote:
Originally Posted by raycow View Post

The O/D unit and midplate might bolt onto a GM case if you drill a hole for the reverse lockout rod. GM pattern T-85/T-89 cases are pretty scarce though.

If it were mine, I would get it apart now just to just to halt any further rust progression. That thing is too valuable to lose.

Ray
Valuable?

Would you cringe if I told you it spent at least a year, maybe two, just sitting out in the yard... coupled to the motor... but in the weeds. I only brought it into the cover after I gave the motor to a scrapper.

I refused to part with the transmission.
__________________
--
- David R Leifheit
in Dallas, Oregon
mailto:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

(2) 1961 1500
1962 1000
1963 2500
1963 4000
1964 2500
Reply With Quote
  #35  
Old July 26th, 2013, 02:50 AM
David R Leifheit's Avatar
David R Leifheit David R Leifheit is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, Oregon
Truck: 1960-1966 1000-4000 series
Age: 62
Posts: 281
Rep Power: 165
David R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the roughDavid R Leifheit is a jewel in the rough
Default Re: 3 on the tree

Quote:
Originally Posted by tatastruck View Post
Sorry to hijack. I have a 64 long bed with three on the tree and they have already relocated it to the floor however I really don't like this transmission so I'm looking to change it to the 4 speed. How hard is that will it bolt up to my existing bell housing?
Since it has already been relocated to the floor, I *assume* a hole has been cut for that. You might try scrounging the wrecking yards to see if there is an unmolested 4 speed floor cover (ie. one with a factory hole in it).

I know that on my first truck, the butcher job done to move the three-speed to the floor would have remained a nasty hole if I hadn't replaced the cover.
__________________
--
- David R Leifheit
in Dallas, Oregon
mailto:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

(2) 1961 1500
1962 1000
1963 2500
1963 4000
1964 2500
Reply With Quote
  #36  
Old July 26th, 2013, 02:51 AM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 101
raycow is on a distinguished road
Default Re: 3 on the tree

Quote:
Originally Posted by David R Leifheit View Post
Since the transmission is -shorter- wouldn't he have to lengthen the driveshaft?
I could have written that better. What I meant to say was that if he had a short SM318 on the truck now, he would have to shorten his present driveshaft in order to use it with the O/D transmission, because all of the overdrives are long.

Ray

Last edited by raycow; July 26th, 2013 at 03:20 AM.
Reply With Quote
  #37  
Old July 26th, 2013, 03:02 AM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 101
raycow is on a distinguished road
Default Re: 3 on the tree

Quote:
Originally Posted by David R Leifheit View Post
Valuable?

Would you cringe if I told you it spent at least a year, maybe two, just sitting out in the yard...
I have already cringed. As soon as I saw your pics, I KNEW it had been sitting out in the weather.

When I said valuable, I meant scarce. You might have to look for a long time before you find another T-85/T-89 with overdrive. If you do intend to use it, you might want to start looking now for a GM pattern case. That won't be easy to find either.

Ray

Last edited by raycow; July 26th, 2013 at 03:21 AM.
Reply With Quote
  #38  
Old July 26th, 2013, 06:17 PM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 101
raycow is on a distinguished road
Default Re: 3 on the tree

Hey guys, one of those overdrives on ebay is gone already, and I can hear the clock ticking on the other one. Going, going.......

http://www.ebay.com/itm/Manual-3-spe...34daec&vxp=mtr

Ray
Reply With Quote
  #39  
Old July 27th, 2013, 06:10 AM
tatastruck tatastruck is offline
Member
 
Join Date: Jan 2013
Location: San Pablo, CA
Truck: 66 Longbed
Posts: 32
Rep Power: 77
tatastruck is on a distinguished road
Default Re: 3 on the tree

Quote:
Originally Posted by raycow View Post
If you get an SM420 transmission (used 67 and earlier) it will bolt to your present bellhousing with no modifications needed. You will need to replace the driveshaft, and, of course, cut a hole for the shift tower.

If you get an SM465 (used 68-up), you will also need to have the bellhousing center hole bored out to approximately 5.125" to accept the front bearing retainer. This is a job any machine shop should be able to do.

Ray
If I happen to find NSM 420 in a junkyard how would I identify it?
Reply With Quote
  #40  
Old July 27th, 2013, 07:09 AM
raycow raycow is offline
Senior Member
 
Join Date: Jan 2013
Location: San Francisco, CA
Truck: 1960 C-10 Short Fleet
Posts: 129
Rep Power: 101
raycow is on a distinguished road
Default Re: 3 on the tree

Quote:
Originally Posted by tatastruck View Post
If I happen to find NSM 420 in a junkyard how would I identify it?
You might want to print some of the pics on this page and take them with you.
http://www.6066gmcguy.org/SM420.htm

Lacking the pics, a quick and dirty way to tell the SM465 and SM420 apart is that the 465 has two PTO covers and the 420 has only one, on the left side. The 420 also has a very significant "bulge" on the right side of the case.

Ray
Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
3 on the tree tinman64 Transmissions and Rear Ends 1 April 6th, 2013 11:49 PM
1961 3 on the tree column Archiver Previous Forum Posts 2 November 14th, 2010 05:34 AM
Re: truck I found under a tree Archiver Previous Forum Posts 0 December 7th, 2008 04:45 AM
Re: truck I found under a tree Archiver Previous Forum Posts 0 December 7th, 2008 12:32 AM
Slight Help for "Three on the Tree" Problems Archiver Previous Forum Posts 0 July 30th, 2008 01:08 AM


All times are GMT +1. The time now is 10:57 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 711710599629|1709632660|0