[91 twin locked]

my gearbox rear seal is leaking have a new one , question is can u replace it in the car ? and is there any treads on here about this or photos thanks in advace guys

[jimny_timmy]

Not sure in a Sierra, but jimny it's simply drop the transfer case and pull the jack shaft off and the seal is there staring you in the face. I'd presume it's going to be the same in a sierra

[DMAC]

Yes you can. Drop out the jack shaft. Prise out the old one. Some good seal picks help here. Gently tap in the new one. Things are snug doing it insitu.