Man.... I had forgotten about this thread until someone liked one of my posts on it today.
Someday I'll get home and buy another property and build a new shop, but it's not in the cards right now. Maybe someday I'll get another M49, but I kinda doubt it at this point. Sucks starting over with no help.
I didn't read through so many years of posts, but in case you didn't get an answer, your truck is an early A2.. Many early A2's had the LD465 with a downspout exhaust.. When I was at FLW in the 70's there were many A2 downspout M35A2's with the LD engine, especially assigned to the Motor Transport Operator's Course training battalion.. In other motor pools you could see a few mixed in with A1 "skinny stacks" and A2 LDT "fat-stacks" .. Yes, and a couple downspout M49A2C's as well..
As these LD trucks needed new engines, I'm sure some got the LDT and changed to a stack... Not all A2's have the stack hole in the fender.. If your exhaust is a downspout, your stack-hole fender is not original to the truck.. On the other hand, LD-powered A2's with stack were out there during my time...
I would date your truck to 1966-67 original A2 since it does not have the visual features on the grille, dash, nor cab floor to indicate it had been the multifuel conversion of an older gasser ..
Same here, divorce ruined/delayed my M49C/A2C fixes as well as many other projects/plans.. Sure sucks when you have to build a whole new life/place all over again.. 16 years, I never rebuilt .. Too old now, there's no sense in it.. Am making do out in the elements with my shop in an M109A3 and most parts in trailers incl M750