You probably have all this crap figured out or researched but I will babble away anyway.
A lot of those Deeres had plugs for the block & transmission/hydraulics. It took a special round plug on a 3’-4’ cord with a built in circuit breaker.
The outlets were under the left hand door.
Dads 7330 had both, his 6155 has both. Chases 6110 only has the block plug.
Block heaters & transmission/hydraulic heaters are probably a special order thing.
If I am thinking correctly those Deeres are equipped with an intake manifold heater, turn the key to the right one click & push in for 20-30 seconds.
Chases 7810’s & my brothers 7410 just have the block heater plug on the side of the block & the intake manifold heater with the key switch.