Could you post some photos of the setup for each?I put an AM 148403 under a Milsco XB 200 on both my X540 and X324. It appears to be the same base as a X700 and 1025R. I also needed bumpers M166745. On one I needed a taller bracket M146750 to get the right angle and ability to tilt the seat. I had to loosen the fender pan and get some stainless philips and nuts too. I started with the X540 and was very pleased. I told myself that I didn’t need to do the 324 for the civilized lawn. I unexpectedly hit a bump one day and I changed my mind. I spent about $1200 on suspension across my three machines this year. My only regret is that I waited so long.
I hope this helps.