[Captainfab]

GM never put a big block in the '67-'72 K series trucks. If you had a C20 instead of a K20 all you would need are a set of '68-'71 C series big block engine mounts and the brackets. The C series engine mount brackets are not going to work with the K series engine mount crossmember. A C series (2wheel drive) crossmember is not going to fit in your K series (4 wheel drive) frame without converting your truck to a 2 wheel drive. I believe guys that put big blocks in their K series trucks, move the engine mount crossmember forward 1-2" and drill new holes. Of course in doing this you will also have to move the transfer case mount forward, shorten your front driveshaft and lengthen the rear driveshaft, as well as all of the other things connected to the engine. You will also want to run the short water pump.