Sandman2234,
The loaders mentioned by everyone are different loaders built over the years for different tractors. For an example the 148 is larger than the 146, and the 146 is larger than the 145. The 148 is usually on 3020's and 4020's, but can also be put on the smaller tractors, but as you said the brackets may not be a direct bolt on. The 20, 30 ,40, 50, 55, and maybe others series all shared pretty similar mounting points and is not to hard to fabricate or change. The brackets can be found if you look around and know what you are looking. Scrounging dealers lots are a good place to look. I had found some brand new never used brackets at local dealers, but ended up finding the exact same pair on Ebay from a JD dealer in W Va. I bought them and had them shipped for less than 1/2 what the local dealers wanted. If I remeber correctly the dealer in W Va sold a few pair of brackets. I ended up putting a Case Model 60 loader I had on my JD 301A. Not all that hard, but tied up some of my free time, that I do not have very much of. You may want to get on John Deere's website and do a dealer search for dealers near you. Then look at the used equipment online the dealers have listed. I would also look at the aftermarket loaders. May save you a lot of time looking and the cost should not be too bad. Finding good used loaders are hit and miss. If you do find a used loader, go over it very carefully. A loader that looks pretty decent on a quick look, can turn out to have some pretty good cracks, when looked at very carefully. Good luck and sorry to ramble on.
Russ