Mounting 1972 SM 465 and 350cu into 67 C-10

[Rich1972C20]

I just tried to install my 350 engine with the bell housing of a SM 465 that originally came out of a 1972 C-10 into my 1967 C-10 that had a straight six and wouldn't you know it the mounting bolts for the bell housing don't align with the transmission mounts on the cross-member.

Is there an aftermarket bolt on solution (adapter) for this?

Any help is appreciated.

['68OrangeSunshine]

You need the bellhousing for a '68 C/10.
1967s had the SM420, which had a smaller pilot diameter.
Or have a good machinist open up the 420 bellhousing to fit the 465.

[Rich1972C20]

Thanks.

I also seem to have a problem with the motor mounts from the 72. They don't line up either. Was there different V-8 motor mounts between the 67 and 72?

[Accelo]

The 72 motor mounts are unique to the 67-72 trucks..
The straight six mounts are different than the V8 mounts.

['68OrangeSunshine]

Was your late L6 a 250 or 292? And if the latter, do you still have the RH or Passenger Side perch and motor mount?
And yes, L6s mount in different frame holes than the V8s. SBCs and BBCs may also have different placing. Still a V8 novice. 1972 differed from the 68-71, I've heard.

[Rich1972C20]

It's a 250.

If I change out the bell housing will the input shaft of the 465 have engagement issues?

['68OrangeSunshine]

Originally Posted by Rich1972C20

It's a 250.

If I change out the bell housing will the input shaft of the 465 have engagement issues?

1] OK. NM.
2] Shouldn't be any engagement issues.
But IDK? We're dealing with technology from 50-something years ago, and that's a lot of POs to mess with things.

This is from my notes:
Bellhousing P/N:3925505 [GM5] has 5-1/8'' ID for SM 465.
Bellhousing P/N:3815891 [GM11] has 4-9/16'' ID for SM 420.

If you can't find a '68 465 bellhousing, a competant machinist can open the pilot hole of the 420 out to 5-1/8''. They used to do it all the time.

['68OrangeSunshine]

I'm sorry. I just re-read your original question. You HAVE a bellhousing for an SM 465, but it won't fit the crossmember mounting holes from the SM420 on the MY '67 Frame.
That's because the 465 is longer than the 420 was. You will have to shift that crossmember aft a few inches [I don't know exactly] and drill and remount the crossmember further back. You may have to shorten the Prop Shaft, too. IDK.

[Rich1972C20]

I thought you read it wrong. I'd like to keep current bell housing. This is what I am currently planning to do:

1) Position the engine so that the Z-bar can be mounted properly (connected to engine and frame).

2) Mount engine mounts based on position from step 1.

3) Based on mounting engine in new position, locate where current bell housing bolts will be and re-position crossmember appropriately.

4) Adjust drive shaft length.

My concern about this is what's happening with fan to fan shroud relative position.

Any thoughts?

['68OrangeSunshine]

Sounds good. if the fan/fan shroud is too far back, you can put an extension on the fan.
Too long, you may need to go from a Long Water Pump to a Short Water Pump if needed.
GM made fan shrouds in different lengths. May have to shop around.
My 350 in the '71 GMC K/1500 Jimmy has a short water pump, Z-Bar clutch linkage, Heddman headers, SM465/NP205/3.73 Differentials.

Funny, I thought I had the answer, but it was for the wrong question.

[CAMAROBOY68SS]

There really is no crossmember on the truck with a SM465, the bellhousing sits on a pad on each side of the frame. The transmission floats off of that. No place to mount a rear crossmember on it. I still have the bellhousing mounts in my frame even thought I now have a Tremec 5 speed in it. I had to add a rear transmission crossmember.

Also if your truck was factory manual transmission, then your frame brackets for the Z bar will be in the rear location due to the I6, then the rod from the pedal through the firewall and then from the Z bar down to the fork are I6 specific.

I dont know if the engine stand frame holes changed from 67 to 68 due to the swap from the 420 to the 465. My 68 was a original 4 speed truck with a 292, swapping to the V8 just meant the small block had to keep the frame stands in the rearward location.

[Rich1972C20]

Camaroboy, what headers did you use? Hedmen seems to be the best fit for a manual.You did a great job on your rebuild.

The crossmember I refer to is the part that the bellhousing mounts too.

[CAMAROBOY68SS]

Originally Posted by Rich1972C20

Camaroboy, what headers did you use? Hedmen seems to be the best fit for a manual.You did a great job on your rebuild.

The crossmember I refer to is the part that the bellhousing mounts too.

They were on the truck when I bought it, when I tore the truck down for the redo I looked all over the headers but found no markings or part numbers. With the headers I did have to flip the Z bar 180 and had to swap the correct Z bar ball on the engine side with a smoothed up Allen headed bolt.