54 Chev 235 was first pressure oiler. You can use a 54 or later 235 as well as a 261. Chev and GMC use different linkage as the GMC engines are longer and even the 235 Chev will use the other pivot point on the side of the block vs. a manual transmission engine. I think Oldsub is thinking 53 when he called it a unique engine. As I understand it, 53 had a 235 that was still a splash oiler. You may want to do some rnnout checks on the crank and the adapter plate opening as well as the torrus neck. There was a plate that stated that trans and engines were a matched set and not to swap them but it is all in the runout checks described in the service manual.
