how can I tell what year the transmission was made?
 

My "new" ranger was owned last by a shade tree mechanic who bought it just to fix and sell. He put a junk yard transmission in to replace the original tranny which had lost reverse.

I think he was competent but just a bolt/unbolt kinda guy. I don't think he knows a lot about Rangers. So, I see that the 98 automatic is supposed to take Mercon V. How do I tell what year the "new" trans was made so I can make sure I put the right fluid in? Is there a serial number or a stamp in the casting? Or maybe the 1997 and newer Rangers won't take an earlier transmission?

I think all ranger transmissions take Mercon no?

1997 and newer take Mercon V, and you aren't supposed to mix Mercon with Mercon V. So I have no idea what this guy did.

Maybe I don't have to worry.
LUBE REPORT: Ford Pulls the Plug on Mercon

All fords are supposed to have mercon 5.