I know this thread is a few years old but for those of us having gone through this problem recently, there's new info out about this issue:
My Massey 1533 has a factory solenoid part #6242128M1 (the solenoid is a Woodward SA-5190-12) which costs anywhere from $245 to $345. If you want to buy the cheap one that fits a Kubota, it's part# SA-4569T for $14.86 and free shipping on eBay or LarryB's also sells the cheap one for $29.99 plus shipping.
The problem is that it overheats and burns up in minutes because of the current going to it. It'll fit great and work but it overheats and burns up.
This is the information LarryB's is telling those of us who want to use the cheap one on the Massey 1533 :
"When using this solenoid on Massey Ferguson 1533 Serial# JVA95201 or lower, an adapter must be used in the circuit to prevent solenoid overheating. Massey Ferguson 1533 Serial# JVA95202 or higher do not require this adapter. This adapter re-routes the power for the white wire on the solenoid to be powered by the glow plug circuit to allow the power to turn off correctly after starting."
The Massey harness is part# 6258743M91 and may be available through your Massey parts dealer. but it's hard to find a dealer who stocks it. I found it online after hours searching for $76.89 plus shipping at Lindstrom Equipment.
If my tractor were newer or under warranty I'd probably buy the harness but since my tractor is 16 years old I just rewired the white wire myself and was done.