sa 250 d problem

[nickestes250]

ive got a code 8912 sa 250 d, it stoped welding so i took the cover off the excited and found that from one slip ring to the frame i had continuity and from the other slip ring to the frame i had it as well, but i have 46 ohms resistance between the two slip rings with the probes on each one, so i figure the rotor is burnt up, i found a sa 250 gas welder with a locked up engine, the face plate looks the sam as mine with the 230 rec and 120 rec for ac voltage, so first will that generator unit work on my diesel rig and how much trouble is it to swap them out?? any help with be great!!