D478 manual transmission identification and options

[Murdoc]

Thanks for the info, do you happen to know what model Clark it was? I looked into the np540, didn't know about them. Looks like a perfect match. Too bad they are rare in overdrive models. I did find a forum thread on a bronco site from 2007 talking about a place in Colorado that apperently was able to rebuild np435's to 5 speeds possibly using np540 gears in the case. Pretty crazy stuff. Too bad the company in question closed in 2002

[BillT]

Not sure what model Clark it was, but the charts over at Jolly's '60-'66 Truck site may help you out. I see that one model Clark had an OD, but I believe they are pretty rare too.

Only thing I can tell you is that along with the 2-Speed Rear, my Clark had an irregular Shifting Sequence:

1L
1H
2L
2H
3L
3H
4L
5L
4H
5H

1L and R were nice and low geared as well in the '62.

My '67 7500 also had the same Shifting Sequence which I believe was also a Clark.

Here is the link to his site:

http://www.6066gmcguy.com/

The Trans info is here:

http://www.6066gmcguy.com/SM420.html

[Murdoc]

As it turns out, the bellhousing for this particular motor has the 2 rear motor mounts bolted to it. So it looks like I'm sticking with the np435 and am just going to have to have it rebuilt.

[Murdoc]

Just ordered replacement clutches and pressure plates from capitol clutch and brake Inc. Great guy, really helped me find the right parts (I hope) for anyone who what's to know, the pressure plate part number is "ILL NCA-330-1938", the clutch part number is "M-458-CV" I can find literature on the pressure plate but not the clutch. In the pdf for the pressure plate you can ignore the "spline size" as that goes for the clutch that comes with that plate, they just ordered a different clutch that has the correct spline and diameter. Just for future people going thru the same issue that I am. I also ordered 2 clutch disks just in case they become scarce. I also was able to find a nos intake/exhaust manifold gasket.

[POWERSTROKE]

BILL T. Seems like GMC used a lot of those Clark 5-speeds with what were called "Working 4th & 5th gears. Guy Dad hauled livestock for had two early '60's GMC semi-tractors, single axle gas powered and one for sure had the "working 4th & 5th. Both were the 72" BBC steel tiltcab. The IH CO-190's with Red Diamond 450-6's had the progressive shift pattern. The same guy bought a new '65 Chevy C-80 short nose conventional single axle tractor that had a TORO-FLOW in it, D-478 I think. If Dad had his choice, he'd always take that C-80 with the Toro-Flow before taking a tilt cab of any style. The trucking company owner traded the two CO-190's for Emeryville's, a 220 Cummins powered tandem rear axle with 5-3, other was single axle with 185 Cummins and 5+2.