Appreciate the info fellows. I measured from the center of the mount to the back of the bell housing and it was the same distance on both sides so, it must be the 250. It has GM66 under the casting number and LMC truck parts catalog gives a 250 in its list of engines for 1966 and I also know that the engine came out of a 1966 longbed. With the pulling power it has, if it was a 292 I probably wouldn't need anything but third gear. (just kidding,) but I bet a 292 does have a lot of power for an inline 6. Again, thanks for the info.
Truck Tinker
