Es150r and es150l if I remember correctly. 3/4-18 thread, same taper as a Scout.
If you want to flip the tr on the top of the knuckles you could. Edit: *** used to sell a "flipsert" that allowed this with the stock taper. Or you could use the bigger gn "1-ton" tre's that use a bigger taper and 7/8" threads and with the proper taper reamer the existing whole diameter will probably be fine. IH only sells a whole kit to make your own custom tr and dl using the bigger tre's, or you can source the parts yourself and save a little money in exchange for labor and effort.
The 3/4 thread "stock" taper stuff is sufficient for most rigs with moderate tires. If your really pushing things the bigger stuff is a good idea, but then you probably wouldn't be running the stock steering arraignment and knuckles at that point either.
Upgrading the tr and dl from the stock pieces to dom pieces either drilled and tapped or with weld-in inserts is such a huge upgrade the ends really don't mater than much,