HT4 questions?

Just got back home from picking up the latest addition to the collection, a HT4 s/n 2659 on a D4 s/n 7U17937SP9 crawler.

I have a couple questions.

1 - I purchased a manual for the HT4 conversion and it is supposed to go to s/n 2800, but in the manual it shows that the loader is bolted on but it is welded & it looks like it never was bolted. Does anyone have an explanation for this?

2 - The main engine has apparently spun a rod bearing & was wondering if the parts from a D4 7U27770 would be compatable to inter-change parts?

Thanks, catcrazy

I have an HT4 parts book covering HT4-101 to HT4-2800 and 35C1 to 35C5307.
All are shown as bolted on.

The engine parts will interchange except that the balancer engine stuff kicks in at sr. #27,570.