I have a 95 Disco I with the auto tranny and 3.9L V8. The issue is as follows:

When it's first started up and I drive away the tranny won't upshift out of first until I hit 4500-5g's rpms (bad idea) or I sit and let the vehicle warm up for a few mins and have the tranny in neutral to circulate the tranny fluid. After it shifts to second, it will act as normal. It seems like it needs to build up pressure in the system or something. I checked in the RAVE and it says that it's probably a sticking primary regulator or a clogged filter. Well I was hoping it was just a filter so I did a fluid change and ran it, then I did the filter and what a PITA that was.... What an engineering marvel! Anyways it still does it although it shifts nicer now. The pan had clutch material and metal shavings as well...

Can I get to the Primary Regulator to clean it and unstick it? Is it in the CONTROL UNIT ASSEMBLY? I have found a used "good" tranny for $500 and I am thinking of attempting to swap it in for mine but I was wondering if I can simply unbolt the control unit assembly and bolt it into my tranny in the truck after dropping the pan? Anyone know if this is possible?

Also how much of a job is a tranny swap in one of these? Do I have to drop the tranny with the transfer case or can I just drop the tranny with the motor and transfer case supported from underneath?

Please any ideas on what the problem is and the solutions would be great. I have a 2-3 day window to get this thing done. I love the disco and want to drive it like it should be driven.

Thanks