1966 gmc

[Rubbertiredtramp]

I am new to this forum. I seem to be registered to the 67-72 site but would rather be on the 60-66 site I dont know how to fix that. Anyway my question is about swapping engines and trannys, I am looking at a 66 gmc i really like because it is a long wide box with a big back window. The body is in pretty good condition. Unfortunately for me it is a powerglide with a mid 70s small block chevy in it. I cannot live with an automatic and dont care much for the V8 either. I have a 292 and sm420 but with the offset motor mounts on the 292 would a 250 or even a 230 be an easier swap? My main concern is motor mounts, crossmembers and getting everything located properly. Perhaps I should keep looking but the BBW is very attractive. Any thoughts on this?
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[Clyde65]

292 did take a different passenger side mount, 230/250/v8 are the same

Btw, the 67-72chevytrucks.com forum page is what you signed up for, there are tons of other GM trucks represented here with their own page.
Welcome to the forum!!

[geezer#99]

I think the tower for the motor mount just gets moved on the crossmember. So the 292 will bolt in.
However if the crossmember for the bellhousing has been removed to fit the powerglide in then your trans won’t bolt back in. The bellhousing mounts on the crossmember and the trans hangs off the bellhousing.
Also the sm420 needs a high hump floorboard for clearance.

[Rubbertiredtramp]

Originally Posted by geezer#99

I think the tower for the motor mount just gets moved on the crossmember. So the 292 will bolt in.
However if the crossmember for the bellhousing has been removed to fit the powerglide in then your trans won’t bolt back in. The bellhousing mounts on the crossmember and the trans hangs off the bellhousing.
Also the sm420 needs a high hump floorboard for clearance.

The 292 and the 4 speed that I have are still in a 66 one ton so I probably would have everything I need to do this If the parts are interchangeable. the pickup is a 1/2 ton. So if the 292 will just bolt in, then the rest should come easy (maybe) then with the tranny in the right location . I could take it to a place that does driveshafts and have that done. It's hard for me to compare the two trucks because they are 110 miles apart. This may seem like a lot of work just to get the BBW. But I think they look really keen, and to me a chevy 6 hooked to a sm 420 sounds like music to the ears. Also I will probably have to change the ring and pinion eventually.

[geezer#99]

Shouldn’t be too hard to swap then.
Give you something to do over the winter.

[Captainfab]

The 292 engine mounts from the 1 ton will bolt right into the 1/2 ton frame.

[Rubbertiredtramp]

On followup, I did buy the 1/2 ton it did turn out to be a 65 registered wrong minor detail. And now I have both trucks side by each so hope to be starting this new project soon.

[bigmoe]

Hello from a fellow Brandonite! I sent you a pm.

[vince1]

It's funny how people's tastes are different.

I just took out my 250 and can't wait to get rid of that loud 4 sp. to put in the auto, but that'll be a spring or summer project. The 250 ran good if you want it and I do have the seal kit for it, but it could use a cam shaft .

A 292 would be a better choice if you can find one because IMO the 250 just doesn't have enough oomph. The 68 short box I used to have seemed to do a little better with it.

[Rubbertiredtramp]

Originally Posted by vince1

It's funny how people's tastes are different.

I just took out my 250 and can't wait to get rid of that loud 4 sp. to put in the auto, but that'll be a spring or summer project. The 250 ran good if you want it and I do have the seal kit for it, but it could use a cam shaft .

A 292 would be a better choice if you can find one because IMO the 250 just doesn't have enough oomph. The 68 short box I used to have seemed to do a little better with it.

If we were closer perhaps we could do some kind of deal, I really like a 292 but they seem to have a characteristic of kind of loping when descending a hill in low gear, I think because of the long stroke, again minor detail.