2 91 rangers 2 different looking 2.9l?
 

I have a yellow 91 ranger with 2.9l 4x4 mfg date 1/4/91. I recently acquired a 91 ranger xlt 4x4 with a 2.9l mfg date 5/91 that I planned on using in the yellow one as it has a cracked head. When I got the doner home sitting next to the yellow one I started noticing subtle differences between the 2. Beginning with the back window. Then the intake manifold, and distributors, one is hei, one has a cap and rotor. I was told the donor was a 2.9l. But now I'm not so sure. Am I wasting my time trying to put the donor engine in the yellow one. Yellow is automatic trans electronic t case. The donor was 5 speed manual t case which I don't have anymore. I have pics of the engines if needed but I have a really slow connection so they are taking forever to load. Thanks for any help in advance I appreciate it, Gregg