To be quite honest I don't know. I've seen a few TDR sevo's for sale and just wondered if they were the same. I've been looking for a 3 wire servo and related part's to fit on my 88 DTR.
iirc they are all 5 wire on TDR's - I had the 'new' shape one.
If you are looking for the 3 wire version keep your eye's peeled on ebay as they were never sold in the UK with this type of servo it was an upgrade that not many owners bought.
I'd imagine that if its only got three wires then there is nothing extra electronic inside of it that might be model specific, the 5 wire ones could have some kind of controller built into them = I dont know!
I've used the free one before and its taken me to D&K spares twice, although they have a poor reputation on prices for used bikes they have sold parts on 2 separate occaisions and been great.