I need some HO scale 100 ton trucks with 36" wheels. Which ones do you recommend?
That depends on what you want, as there are several good products. ExactRail’s look great and work well, but their site currently shows them as out of stock. I also like the Athearn Genesis trucks with rotating roller bearing end caps http://www.athearn.com/Products/Default.aspx?ProdID=ATHG4595 code 110 wheels, http://www.athearn.com/Products/Default.aspx?ProdID=ATHG4599 code 88 wheels. Tangent offers a nice 100-ton truck https://www.tangentscalemodels.com/product-category/trucks/ .
If you don’t mind doing a mix ‘n’ match, Accurail sells sideframes separately and you can add metal wheels; both ExactRail and Intermountain wheels roll very well in them, and others work too http://accurail.com/accurail/parts.htm . Accurail’s standard-issue one-piece plastic wheels aren’t the greatest.
Kadee trucks aren’t bad overall, but I’ve come to prefer machined wheels over Kadee’s cast wheels (they have voids in the metal due to the manufacturing process used [sintering] and they can accumulate crud during operation, even if you polish the treads). Their newer “HGC” plastic trucks do look good, so they may be an option if you don’t mind the wheels (or are OK replacing them). Kadee’s bolster design may also require modification of the body bolsters on your cars.
Walthers/Proto 2000 are nice as well http://www.walthers.com/exec/productinfo/920-21256 . While older Proto wheels were also sintered metal, they didn’t seem to be as prone to collecting dirt as Kadee. The down side was they sometimes weren’t square on the axle