There is a book about old gas Cats by a fellow named LaVoi. I am not sure of the spelling but he talks about some of the undercarraige being the same. I dont have the book in front of me but remember him saying that. If no one has given better information by Friday, I will bring the book home and post what it says. Grant.
Rails and pads are interchangeable I'm pretty sure as the rails are the same pitch. Entire sprockets don't exchange because the D2 uses splines in the hub and the Twenty-Two uses a keyway (maybe a cross-over very early on?) but the replaceable rims will exchange. I don't know about rollers and idlers
This book available on Amazon.
Caterpillar Gas Tractor: Restoration & Interchange Manual Paperback – December 1, 1996
by Bob Lavoie (Author)
Paperback
$11.23
8 Used from $11.23
2 New from $46.17
Book by Lavoie, Bob
beesbo, that is the book that I was mentioning. It gets criticised an I have seen a few errors but overall there is a lot of good information in it. Grant.