Question on 1971 Frame

[11555wally]

I've been looking at a 1971 C10 that is pretty good condition with thoughts on buying it. On the glove box door it says it is a 350CI and a 350 trans. It doesn't have an engine or trans in it which is ok with me. My question is there appears to be an engine mount on both frame rails just below the firewall. They have been cut within about 2 or 3 inches of the frame rail. Not having owned one of these before I'm not sure what it is there for. I was under the impression that the rear mount was a crossmember back further from the firewall. Could it have been a frame for a standard shift transmission, a 6 cylinder engine, or what. Thanks in advance for any help.