I have discovered my linkage between between the shifter and the lever underneath could be the reason why when I shift into 4HI the TC is in 4PT.
Trying to shift back into 2HI requires reversing a few times before the TC adjusts.

The Novac upgrade looks good to place the stock links, but Im appear to be a bit of a noob with finding the bolt I need to adjust:
From other posts I need to:

Loosen the bolt, stick a 1/8th drill bit between the back of the shift plate and the shifter, pull back on the shifter, have someone tap on the trunnion and lube it till it slides into position. Then have them tighten the bolt back down.

Where is the trunnion? I had a look underneath and the rubber bushing seems loose. Couldnt tighten it as I thought it would snap off.

Anyone have a write up or pictures for dumbies on this?

 

It would help if we knew something about your vehicle. Please fill out your info in the User CP. The trunnion is a block that a screw is threaded into that secures the shift rod. Spray it liberally with PB Blaster several times before trying to loosen it.