Cub 1872 rear pto fit on 1782?
 

Will a rear pto off a cub 1872 fit and work on a cub 1782 cyclops?

Maybe, check the parts lookup.
Compare one to the other here...

https://www.cubcadet.com/webapp/wcs/...0-A/0071800001

Yep. :beerchug:

433 (190-433-100) - Cub Cadet Rear PTO Kit
Attaches to these other models:

Cub Cadet 984
Cub Cadet 2084 S/N 836,000 - 864,500
Cub Cadet 1914
Cub Cadet 1872 & 2072 S/N 756,300 - 799,999
Cub Cadet 1772 S/N 756,300 - 799,999
Cub Cadet 1572 S/N 756,300 - 799,999
Cub Cadet 2082 S/N 800,000 - 821,059
Cub Cadet 2182 S/N 821,060 - 880,000
Cub Cadet 1882 S/N 800,000 - 821,059
Cub Cadet 2182 S/N 816,536 - 821,059
Cub Cadet 2182 S/N 800,000 - 816,535
Cub Cadet 1782 S/N 821,060 - 889,000
Cub Cadet 2284 S/N 864,501 - 899,000
Cub Cadet 2082 S/N 821,060 - 836,000
Cub Cadet 982
Cub Cadet 1782 S/N 800,000 - 821,059
Cub Cadet 986
Cub Cadet 2086 S/N 880,001 - 899,000
Cub Cadet 1912