Only Cub Cadets - Cub Cadet 417 with loader where to check hydraulic fluid

New owner of a 417 (7274) with loader and PTO set-up. My guess is that it was made in the 1970s or so.

I'm unsure where to check/add hydraulic fluid and the specific type of fluid.

No tag number for serial #, etc. I looked all over, seat, under seat, frame, nada. There's a tag on the engine (3 cyl diesel) but that's not the one. I called Cub Cadet in Ohio, phone parts-gal says the tag is under the seat. Nope. It ain't. It looks like the original seat too and not a replacement. Supposedly the serial number should be 11 numbers/letters. I see nothing with 11.

I'm also wanting to get my hands on a service manual for it - not the owners manual. I went to the Cub Cadet website but can't access a service manual without serial numbers. A massive google search left me high and dry on the recommended fluid type, where to add it and the service manual.

I just rebuilt the loaders single lever control valve and need to check/add fluid but I'm unsure what type of fluid and where to add/check it.