Which Trail Master do you mean?? The orange one has a H50 Tecumseh 5hp.It has the plate that bolts on the bottom of the block. On the first page of my Sears Project thread I posted the numbers. They were Sears numbers, but Tecumseh Made them. I think they came with a Tecumseh HS50, which is a little smaller block, and doesnt require the stamped metal mounting plate. The blue ones came with a 4hp.