'66 1500 slipping out of second gear

[ilvracn]

i would suggest finding an older junkyard to get a used trans for parts. there are still a few mom and pops style junk yards out there. those trans are still out there, but it will take some looking. i have a used one i would sell, but i am quite a distance from you.

[Harleyq]

Knotts, I don't know what the expense would be of having one cut at a shop. I was a machinist in a former life lol I know it could be done especially with today's cnc's, I used the good old manual lathes and mills. Ilvracn, that is an option but depending how far away ya are the shipping costs would probably negate the feasibility. What I've found isn't bad and a couple of light tack welds and reshaping would be a breeze. Since I wouldn't ha e to do any heavy welds it shouldn't heat up enough to cause a weak spot, thinking out loud here, which is painful at times lol...

[ilvracn]

i agree on shipping costs. i'm from atlantic iowa, south west corner, between omaha and des moines. i see you are from oregon, trans would have to be shipped on a freight truck.

[George Bongert]

Originally Posted by Harleyq

Good morning, I think, folks. The filling station was no help on this one George, however, they can help on other needs. Having searched searched far and wide and the internet too, I have learned a couple of things. 1 they no longer make parts for the sm420, I know big surprise there and 2 if ya see the part ya better get it quick. I ha e found a couple of used 2nd gears which I was trying to stay away from but have no choice but to get one. My question is this, there is some wear on some of the teeth is it possible to do so e tack welding and grind back to shape? Without causing any weakness at this spots? I've got the skills to do it just can't remember if it will cause a weak spot if I do that. Anybody else try this?

OK. Let's try this again. I have located a complete SM420 transmission that is marked as being a good transmission. Unfortunately, it is located a long way away from you. Used internal parts (as well as new ones) are next to impossible to come by. The transmission is located in New London Wisconsin at Highway Truck Parts, E9517 Crain Road, New London WI 54961-8520. Phone number is 920-982-3960, ask for Blair. The price of the complete Transmission is $300.00. I don't know how much you are willing to spend, but this is another source of parts for GMC Trucks. Now, another thing that is worth noting is that Highway Truck Parts has a selection of used parts for the GMC Big Block V-6 engines ranging from manifolds, crankshafts, cylinder heads, and other parts, but for anyone needing used engine parts, or other parts, I would suggest giving Blair a call at 920-982-3960. Highway Truck Parts is another source for Big Block parts that are getting increasingly harder to find. I hope this information helps you, or anyone else interested in finding parts that they may be looking for, and have been unable to find elsewhere.

[Harleyq]

Thanks George for the heads up. Sounds like a decent deal if I have to go that way. I haven't given up finding one locally yet. I just haven't turned over the right rock...

[George Bongert]

Originally Posted by Harleyq

Thanks George for the heads up. Sounds like a decent deal if I have to go that way. I haven't given up finding one locally yet. I just haven't turned over the right rock...

The only drawback to obtaining parts so far away from where you live is the dad gum shipping charges! The price of the Transmission is reasonable, but the shipping charges are killers! Still, Highway Truck Parts is another source of hard to find Big Block V-6 parts. Good luck, and let us know what you find, and where you found it. We need all of these sources to keep those GMCs trucking!