I just found a p38 with a bad transmission this is a 1998, also got a 97 discovery 1 for parts and got the trasnmission and i was thinking to install this tranny on the p38, so my question is this, this is perfect fit? i know the transfer case is the bog barner type and the disco comes with the lt230

 

They are very similar transmission, but definitely not the same. You could try it out if you wish, but supposedly the 95-99 Disco transmission was the same as the one on the defender. The P38's is modified for the H-gate. Whats wrong with the transmission on the p38, specifically the symptoms?

 

I'm not sure, i'm buying this truck without a transmission, i did once change on a 93 rr that comes with the bog brn t/c, I change it to lt230 without problems, everything was a right fit. The only thing i notice betwen the two transmission is a black pug on the left side, on the p38 the plug is coming out to the front of the transmission and the disco transmission the same plug is on the same side but is coming out on the opposite way, like looking to the back, do you understand? but in the same spot, the cable reach to the plug with no problems.

 

They are different in more ways than one, I am sure you can make it work but it may not be worth the hassle. Last time I swapped the tranny in the Range I was able to find a good used one for $600. I think the issue is on how it is controlled, meaning that little black plug that you are talking about. If you are going to buy it then look around and see if you can source the right tranny for a good price.