Hi Anthony, welcome to MLMF.
I did a little poking around and found this on the John Deere Green Part store.
John Deere Complete Transmission Assembly- MIA10318
You might have already found this out, but if not, it might help in locating a transmission to replace yours since it was evidently used on so many different models.
"You're never too old to do goofy stuff."
Hondas - HR17PDA, HR17EPA, HRS21SVA, HR214PXA, HR214SXA, HR214SMA, HR215HMA, HRTZ215HDBW1, HS35, HS622TA, F200A, FG100A1, H4514
Jacobsens - 1949 26" Lawn King, 1961 18" Turbo Cut, 1960 8" Edge-R-Trim
Other OPE - 1960s Tillsmith front tine tiller,1974 Suburban SS/16, mid 80s Jari 36" sickle mower, 1998 Toro CCR PowerliteE, 1998 Lawn Boy Model 10122, 1999 MTD 21" Walk Behind, Stihl MS290, Stihl MS192T