305/351 to 5 speed manual

[Clyde65]

Can it be done? T5 or NV3500 or? Is there an adapter available? Currently have a 4 speed on floor, thanks in advanced!
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[franken]

Look at the bellhousing to engine bolt pattern. The links seem to contradict each other. A normal Chevy type BH pattern has a peak in the middle but many pics seem to show a BOPish pattern.

https://www.google.com/search?q=gmc+...hrome&ie=UTF-8
https://www.google.com/search?q=gmc+...4UtmYWQbmFg7M:

[raylube]

GMC v6 has it's own bellhousing to engine pattern. Check on 6066 gmc website but I think the only difference between this swap and sbc is the trans input opening on the bell housing is smaller as is all sm420 trans compared to later sm465 would need machined. Novak can machine or other good machine shop.
Input splines on clutch discs may be the biggest problem on disc because chevy disc wont clear flywheel to crank bolts.

[Clyde65]

I was really hoping for some good news, I’d like to get rid of the granny 4 speed. I may just do a floor shift automatic then, 7004r
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[Blue666(2)]

Is your current trans to bell housing bolt pattern a Muncie pattern? If so one of these adapters may work so you can use a Ford pattern or GM post 94 T5 on your current bellhousing.

https://www.hotrodworks.com/product-...sion-adapters/

There are some great threads on here about T5 swaps. I would measure everything then call before placing an order.

[raylube]

Those adapters should work. If you want the auto trans you will also need a adapter I think from a place called thornsens not very cheap. Just find your bore size this may help From the Novak site will help you determine size of of bore. As the reader will conclude, the Chevrolet and General Motors SM420 will marry directly to a GM style bellhousing. This includes early (1955-1967) Chevrolet / GMC truck, Chevy car, Buick, Oldsmobile and Pontiac bellhousings . It is important that you measure the locating bore on the bellhousing to confirm the 4-11/16" diameter before performing the swap. If you need to join this transmission to a GM truck bellhousing (versions from 1968-1991) with the 5-1/8" bore, it can be done. Novak offers a bellhousing locator sizing ring, part #BR4. We also sell new, billet steel SM420 bearing retainers turned to the dimension you require.

While the Muncie 420 can be used with any GM engine having the "regular" GM transmission bolt pattern, this transmission installs more easily with the open bottom Chevrolet bellhousings because the lower holes in the transmission case are threaded rather than drilled for clearance. The threaded hole case cannot be modified, so the lower attaching bolts must be installed from inside the bellhousing. If you can find a od trans with a input shaft splines the same as the gmc v6 with one of those adapters so you can use the gmc disc will be your best fix. The gmc dics are 10 spline and hard to find . I had mine reclined by six states. Look for clutch rebuilder in your area to see if they can fix you up.