Aye it's not easy to found those, the best source is "Sterling T26 Discovered" by Steve Hodges but that is a rare thing. Trailer imo can be created in rather easy way, you take that picture:
This is probably an M26 (but without muzzle break?) so we can take that is done by as always invaluable DP and scale the trailer according to the size of tank. Maybe not the most precise way but it should work.
T26 is probably the most impressive truck ever made in my eyes and if you don't have time or anything I can take it from you and finish.