[MTB98]

The engine is either seized or its not. Idk how it can be seized on one side only. Does it turn over with the starter or by hand?
That’s not the original engine. You can look for another one of the same model and swap
It out, rebuild what you have or swap it some other engine (may require a lot of work!)
Those are good little tractors, although getting up there in age. The ergonomics aren’t up to modern standards. It’s up to you how much money you want to throw at it. Sounds like you’ve already invested a decent amount.

 

[MTB98]

If it's the original Kohler 17hp engine and it's seized up, it's not worth fixing. They were notorious for failing. At some point, Deere changed to a different variant of the engine that had pressurized oil and better lubrication to the crank. I have no idea how to tell the difference between the two, but I bet Google knows.

Best,

The original 317s had KT17 engines with splash lubrication. They had a high failure rate and the later models had KT17 Series 2 engines with an oil pump. Deere replaced a lot of the Series 1 engines that failed with Onan engines. These things are 40 years old or better so the original Series 1 engines are pretty scarce. The Series 2 says “KT17 Series 2” on the engine sheet metal.
The OP has a later model Kohler that’s already been swapped in.

 

[MTB98]

@rmorris1 Do you have any attachments for your 317?

 

[MTB98]

Maybe post some pictures of it. I’m sure the guys here can help you come up with a sale price for you to put it on CL of facecrook

I’m not very far from rmorris1. My son has his own 317 he bought when he was 9-10 years old. He may be interested.

 

[MTB98]

Don't forget it's at least 30 years old and could be approaching 40.
(which is great if that's what your after...but not so much if thinking it's only 10 years old)

318 Lawn and Garden Tractor
MP1128 A.1
1983 Model (Serial No. M00318X222001-285000)
1984 Model (Serial No. M00318X285001-315000)
1985 Model (Serial No. M00318X315001-360000)
1986 Model (Serial No. M00318X360001-420000)
1987 Model (Serial No. M00318X420001-475000)
1988 Model (Serial No. M00318X475001-595000)
1989 Model (Serial No. M00318X595001-999000) *
1990 Model (Serial No. M00318X010001-100000) *
1991 Model (Serial No. M00318X100001-110000)
1992 Model (Serial No. M00318X110001-120000)
Note: Regard 1990 and later model serial numbers (010001-120000) as higher than 1989 model serial numbers (222001-999000) when using
microfiche and ordering parts.
(

OP has a 317, built from 1979-1983. A 318 was a more refined version with power steering and built on an open frame with Onan power.