So here is the deal. My brother has a few rovers and wants to build each for different things. He has a SIIa with Arb airlockers front and rear. He also has a disco which needs the third to be replaced.(broke carrier/pin/spider gears) Anyways what would stop him from pulling the SIIa thirds and replacing the side gears for the disco splines? The 10 splines in the Siia broke in the parking lot at safeway playing with the locker. We have agreed that the Siia needs an axle swap to hold up light rock crawling/trail wheeling.

If it's a D-I the third members do swap.
I am not sure about the side gears, never actually done it myself, but have been told they can be swapped.
I know that older RRCs had 10 spline side gears.

The Series has a 4.7 R&P the IDsco has a 3.54

Keep the 10 spline ARBs and get a set of these http://www.seriestrek.com/

So here is the deal. My brother has a few rovers and wants to build each for different things. He has a SIIa with Arb airlockers front and rear. He also has a disco which needs the third to be replaced.(broke carrier/pin/spider gears) Anyways what would stop him from pulling the SIIa thirds and replacing the side gears for the disco splines? The 10 splines in the Siia broke in the parking lot at safeway playing with the locker. We have agreed that the Siia needs an axle swap to hold up light rock crawling/trail wheeling.

Do you want my old 24 spline carriers? Let me know.

Cheers Andy