Just in case you weren't paying attention:

The ACF Car Plant auction at Milton, Pa. listed below includes THREE GE side-rod 45-tonners:

https://www.bidspotter.com/en-us/auctio ... f3015b6080

https://www.bidspotter.com/en-us/auctio ... f3015b6083
Serial number 15154, built GE Schenectady Feb. 1942, rebuilt August 1954 and November 1989.

https://www.bidspotter.com/en-us/auctio ... f3015b6088
Serial #17824, rebuilt at Pittsburgh Jan. 1967.

Also:
https://www.bidspotter.com/en-us/auctio ... f3015b6093
Cummins 1980 N-855-L3 engine with generator for a locomotive, 195 hp.

Good luck.

Anyone know if the N855 is what ACF upgraded their 45 tonners with or are they still HBI600 engines?

COMPLETELY from thirdhand, potentially mis-remembered info, and the people at ACF who would know have moved on or passed on:

I believe the #8 and #9 got a full rebuild by McHugh, and McHugh was noted for offering the swap-out of old engines with Cummins N-855's. The photos seem to show (and I guarantee NOTHING) that 8 and 9 got N-855 swap-outs while #7 retains its old engine.

This one source I'm looking at says that a common retrofit replacement for the original HBI600 engines was the later H-6-BI engine. I can't believe #7 is on its original engine, but it also doesn't look like an N-855.

Heck, go through the rest of the auction and you may find spare GE 733 traction motors........