'86 K30 front driveshaft-slip spline lengths?

[AJMBLAZER]

Big Ugly is a '86 Chevy K30 M1008 CUCV. That means a TH400 and NP208 and a Dana 60 front.
Right now it's sitting on jackstands in the garage while I make the 38's fit. Part of that process is moving the front axle forwards via ORD zero rates.
I can do 1" or 1.5" with their kit.
The front axle is completely drooping right now with nothing under the diff or suspension. Sheer gravity pulling that sucker down.

I just checked the length of the visible splines on the slip portion of the front driveshaft and I can see 2". I guess I'm wondering how much is engaged with the forward part of the shaft right now? Anyone have any idea?

I'm trying to figure out if I should move the axle forwards 1" or 1.5" while still having a safety margin to keep plenty of spline engagement on the front driveshaft.

 

[AJMBLAZER]

Welp...got my answer while dropping the axle.

Was trying to see if I could tug it forwards while it was just barely held on by the last threads of the u-bolts and with the jack barely keeping it level...nope.

The d-shaft came apart before I even moved it half an inch forwards.

Guess it's only getting a 1" lift in the front and the axle isn't getting moved forwards at all. Hopefully I can muscle the thing around enough to get the shaft back together.

Probably going to have to do some more trimming now.