and the question the day is.... how worn out are the holes in bucket and in the FEL arms. that right there is what going to matter. along with how oval the holes have become.
it may come down to welding a piece of metal on each side of the FEL arms, with a good clean holes. so any new pin ya use isn't immediately destroyed in first couple uses. when i say destroyed, i mean bent and wobbled out completely.
i am also assuming there are no bearings in the old tractor. granted there may be bearings and if so... you might want to replace them. so when ya going down the road / driveway with nothing in the bucket, the bucket is not there "chattering away at ya" from the slop of a holes in the bearings that have worn down.
another option might be if no bearings. is drill the holes slightly bigger. to remove the "oval shape" and use a bigger diameter pins.
John Deere Home Page Redirect has a descent "parts" catalog right on there website, i would imagine your tractor is listed along with parts diagrams, and parts numbers to go with them. perhaps even an updated parts number to order new stuff.
the tractor might be listed under agriculature and if not try industrial portion of there website. "i don't have a clue about your tractor so covering me rear"
if ya got a parts number call a local johndeere / tractor places near you. they should all be able to pull up your tractor on there computer, via special logon most likely to john deere website for dealers. and then cross reference part numbers to something they might have. but most likely will have to order the part in for you. p.s. give them the model number, and if you serial number of your tractor in case different version come up, they might aslo ask for make/model of the FEL since there are 3rd party FEL's that go on different tractors from old days to still today.
if you have a caliper (spelling) to measure inside diameter of the holes the pins go through, might be a good route to go.