Correct the RR3000/3500 is a completely different lift. You would need the 35RRTT manual for parts. Typically you just use the serial number to identify the parts as the mast and power unit are built together so the serial number is linked with the mast. The only difference you'd need to look out of is that it is a TT mast and not a TL mast. With a lift this old, I'd recommend calling crown to ensure you get the right parts.