Locking diff components

Hi I've just bought a arb locking diff off ebay. I have a single arb diff and compressor set up allready. I need to buy the solenoid and switch ect to run my new diff on the front. Does anyone know if you can use the ashcroft components? They are way cheaper then arb, the arb solenoid is £80! where as the ashcroft is a mere £18 the only differance I see is the ashcroft stuff is 5mm rather the 6mm on arb. Guess I would have to change the air input on the diff as well? Cheers for any tips, jim