Jose,
I guess the biggest help in your construction, would be Reference Photo's. I've built two or three examples of the Monogram T-28, to include the massive modification required to convert the B/D Model into the A Model (high canopy/small cowling/different exhaust ports). During the time these projects were done, the modifications were all scratchbuilt from my spares box, because aftermarket sets weren't available then.
There are a few area's on the Monogram Model that come to mind:
(1) If going to build it with the canopy open, you'll have to cut the forward transparency and canopy frame from the fuselage.
(2) The dorsal fin needs to be built up just a small amount.
(3) The front gear door needs to be 3 Piece, instead of one.
(4) The main gear outboard doors are two piece instead of one... (lower section is overlapped by upper section)
(5) The main gear tires should be thicker. (the nose wheel on X-Navy aircraft were thin, flat contact surface, solid rubber tires, so the kit supplid nose tire works fine)
Also, if you're going to apply the Arrestor Hook, like's on the "D" Model, you'll have to cut and refinish the section of fuselage underneath the vertical stabilizer.
Remember... reference photos, reference photos, reference photos.
Such as....
http://www.kiwiaircraftimages.com/trojan.html
Frank