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Old February 7th, 2021, 05:45 AM
BillT BillT is offline
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Join Date: Jan 2013
Location: Moneta, VA
Truck: Drove and Owned Many
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Default Re: D478 manual transmission identification and options

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 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:

The Trans info is here:
Drove and owned many, but some of the more interesting ones were:

-'60 GMC 2500 Dump, 305 V-6
-'62 GMC 4000 Flatbed, 305 V-6
-'62 GMC 6500 Flatbed Dump, 478 V-6
-'67 GMC 7500 Box, 6V-53 Detroit
-'71 GMC 9500 Flatbed Dump, 637 V-8

Last edited by BillT; February 7th, 2021 at 06:00 AM.
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