Try contacting Motive Gear. I have had good success getting T5 parts from them. Went through my local axle and transmission machine shop to order. On a quick look at their on line light duty transmission catalog I did not see SR4 parts but I did find that they have rebuilt SR4's for sale. Hence they have SR4 parts for their use and probably for sale. They have several catalogs and the SR4 parts may be in a different catalog. Worth a phone call.
I have also had success cross referencing transmission parts with corresponding Jeep products.
Quadratec and 4WD hardware are also potential sources for parts.
Good Luck