can the u joints from the rear driveshaft be used for the front axle u joints.they look similar...?85 bronco2

 

your best bet would be to just get new ones so you have the proper retaining clips. new ones should only be around 10 to 15 bucks each.

 

Are you looking to use u-joints for the rear driveshaft on the front axle-shafts? I don't expect they would work. The u-joints on the axle shaft are (likely) smaller than the ones on the driveshafts, and have an internal snap-ring instead of the external snap-rings that usually come on driveshaft u-joints.
If you are comparing the rear driveshaft u-joints to the front driveshaft u-joints, they might be the same. Search a parts houses website (www.autozone.com, www.partsamerica.com, www.napaonline.com) and see if you get the same part number for front and rear driveshaft u-joints.