Off the wall question, hope someone can provide some insight.

I took a lower tray deck from a dead WC M24 and put a Phaser 7750 on it thinking they were exactly the same.
The 7750 recognizes the additional trays and will allow paper to be fed from them but it will stop with a jam as it should be exiting the LTD into the printer as if a signal has not been received that paper is entering.
I did notice that the M24 LTD connector has more pins in it than the receiving jack on the printer has.
So, I was wondering if anyone has done this swap before and whether I need to replace the LTD board and wiring harness or what?

Thanks for any info.