261 Truck Engine

[Grant Bowker]

Chris,
I'm curious which numbers are the confirmation that this is a truck engine. I checked today on a Pontiac 261 I bought a couple of years ago and the cylinder block, cylinder head and intake manifold numbers in the ad all match my engine. Why do I believe my engine is a Pontiac engine? The seller said so, he had removed it from a car that he still had to put in a V-8 and he had before and after photos of the car.
I don't see what I think of as one of the prime identifying points of the truck engine on the advertised engine - the large diameter oil filter lines. The automatic choke also seems more car than truck in that era.
I agree that the 261 is an easy (and noticeably more powerful) swap in for a 216 but "physically identical" is a bit of a stretch. The water pump is in the block instead of in front of the block and head so an adapter plate is needed to relocate the 261 fan to be centered on the radiator similar to the 216. The carburetor is different and the tinwork for the pushrods and valve cover requires some camouflage. The 848 head is also differently shaped so the CMP oil filter mount doesn't quite fit, even with the special CMP head bolts.