Find a wrecking yard that removes the driveshafts and has them in a pile or rack---measure input shaft yoke-probabally 3" accross yoke and check rear differential probabally the same --and find correct length driveshaft--with same measurement yoke.Don't forget to leave yourself an inch or inch and a half so driveshaft don't bottom out in trans tailshaft or too short as to allow to fall out.Generally you can see wear mark where input shaft has been riding in seal,good hunting.