'85 F250 4x4, Borg T-19. It's leaking from between the main case and the extension that goes to the t-case. The FSM is pretty useless here; it shows a breakdown of the 2WD version with the yoke, which shows where the oil seal is. But the drawing of the 4x4 version doesn't get that detailed (thanks, Ford!). So I'm wondering, what seals the tranny at the rear on a 4x4 truck? Is there a shaft seal right at the back of the main case? Is it back by where the extension bolts to the t-case (which would mean the joint between the case and the extension would have to have a sealing gasket, right?). Anybody know where a detailed diagram could be found, that includes the 4x4 version of the tranny?

 

theres a gasket sealing the extension housing to the main case and a gasket sealing the extension to the T-case. i used the black RTV silicone when i did my T-case swap. though i would mention that there is a seal on the input side of the T-case tho

 

So does that mean there's no seal on the shaft? IOW, if you don't drain the tranny, and you pull either the t-case off the extension, or the extension off the tranny, it dumps the tranny? If that's so, then it must be that tranny-to-extension gasket, 'cuz the other one's dry.

And it's def the tranny that's leaking. It's gear oil, and the t-case takes ATF.

 

i had that happen on a NP435 once. all my bolts rattled loose and hammered out the gasket. i ran it dry for about 5 miles with it howling, before i could fill it up.
IIRC every connection should have a gasket, paper or RTV, your choice. if i remember right, the extension housing holds the bearings forward, so if its holding the bearings in place, you know its got oil on it.
usually there's a minimum of fluid at the gasket between extension housing and t-case, but even so, i would put a drain pan in place, pull the case back 1/4" and wait to see

 

So I just wanna be sure I'm picturing this right. There's no seal on the shaft as it comes out of the gearbox like on the 2wd version, and you have to gasket the extension to the tranny casing, and install a gasket when you mate the t-case to the extension. And then when you fill the tranny, the whole extension is flooded with gear oil. Is that how it's all put together?

Or does the extension bolting to the tranny create the seal?

Since the friggin' FSM is silent on the subject, does anybody know where there's a little better pictorial info?