Engine/Transmission Question

[brandster]

The 72 truck I have now originally came with a 307 and turbo hydra-matic trans. The engine and trans was no longer in the truck when I purchased it. Will a 350 engine and turbo 350 trans fit the same as the original engine without having to alter any cross members or anything else?

[jocko]

yes

[geezer#99]

Maybe might be a better answer.
Tailshaft length can be different making rear mount position different.

[jimijam00]

Chevy used some smaller mounts on the 307 some of the time during that era, so may not necessarily be a drop in.

What "turbo hydramatic" did your 307 have originally? Wasn't it a "turbo 350"?

[brandster]

Originally Posted by jimijam00

Chevy used some smaller mounts on the 307 some of the time during that era, so may not necessarily be a drop in.

What "turbo hydramatic" did your 307 have originally? Wasn't it a "turbo 350"?

I have no idea, the SPID sticker says M49 Turbo Hydra-Matic

[pjmoreland]

Someone mentioned on another post recently that the smaller engines like the 307 received a TH350 when a Turbo-Hydramatic was ordered, or a TH400 on a larger engine. You might look for remaining evidence of an electric kickdown switch in the gas pedal assembly or associated wiring or hole in the firewall that would have been used by a TH400. If not present, then your truck probably had a TH350.

A lot can happen to a vehicle in 49 years. It could have been through multiple engines and transmissions in that time period.

Post some photos of the engine mounts, transmission crossmember, transmission shift linkage, and driveshaft yoke, and the people here will more than likely be able to tell you what was in there.

[Mike C]

I’ve never seen anything but a TH350 behind a small block in a 1/2 ton truck. Big block 1/2 tons got the TH400 but 307 or 350 in those years would have a TH350. I have a ‘69 3/4 ton truck that has a 350/TH400 combo and I have a ‘72 3/4 ton Suburban that has a 350/TH350 so those combos do exist.

I’ve never heard about smaller motor mounts? All of the small block 67-72 trucks used the same through bolt mount where the bolt comes in through the middle of the stand. Some are physically smaller appearing because they do not have the safety interlock arm on them but they bolt in the same way and the rubber mount is the same.

[MARKDTN]

Originally Posted by Mike C

I’ve never seen anything but a TH350 behind a small block in a 1/2 ton truck. Big block 1/2 tons got the TH400 but 307 or 350 in those years would have a TH350. I have a ‘69 3/4 ton truck that has a 350/TH400 combo and I have a ‘72 3/4 ton Suburban that has a 350/TH350 so those combos do exist.

I’ve never heard about smaller motor mounts? All of the small block 67-72 trucks used the same through bolt mount where the bolt comes in through the middle of the stand. Some are physically smaller appearing because they do not have the safety interlock arm on them but they bolt in the same way and the rubber mount is the same.

Agree. As far as I know all small blocks from '55-'03 have the same common mounts on the block from a 262 all the way to a 400 and everything in between. There are different motor mounts along the way, but as far as I know 283/307/327/350 in a given year have the exact same motor mount. So there should be no problems bolting a 350 in where a 307 was taken out.