The S4QL-D engine is from a Mitsubishi family of off road engines.
There is a variant in Marine too.
You need to see if a re-power complete running engine like this one would work in your machine.
S4Q MITSUBISHI ENGINE WITHOUT DYNAMO, STARTER_SURPLUS PRODUCTS | eBay
Mitsubishi S4Q Diesel Engine – Japanese Surplus Import
• Condition: Surplus engine in excellent working condition, sourced directly from Japan.
• Important Note: Replacement parts included have minor modifications (gas cuts) intentionally done by the supplier to protect the Mitsubishi market. These parts are easily replaceable if needed.
• Engine Highlights:
• Model: Mitsubishi S4L Diesel Engine
• Strong, reliable, and efficient performance.
• Suitable for industrial machinery or automotive applications.
• Why Choose This Engine?
• Cost-effective alternative to a brand-new unit.
• Engine itself is in great condition with minimal part replacements required.
Please Note:
• This is a surplus product, not a factory-new engine.
• Photos represent the actual engine. Feel free to message for additional details or specific questions.
Or this one,
https://www.navalmotor.com/mediaserver/web/mitsugen/manuales/Ficha_Tecnica_S4Q2.pdf
The LS R4010H tractor has the identical engine,
https://www.tractordata.com/farm-tractors/007/8/2/7822-ls-r4010h-engine.html
The Montana R4944 uses the same engine too.
https://www.tractordata.com/farm-tractors/003/4/7/3473-montana-r4944-engine.html
Montana tractors,
MONTANA+Tractors 4940 SERIES w / Mitsubishi S4QL Eng.
MONTANA+Tractors 4944 SERIES w / Mitsubishi S4QL Eng.
other LS models,
LS+Tractors U5020 w / Mitsubishi S4QL Tier III Eng.
LS+Tractors U5020C w / Mitsubishi S4QL Tier III Eng.
Found in the McCormick tractors,
McCORMICK+Tractors CT50U w / Mitsubishi Diesel S4QL Eng.
McCORMICK+Tractors CT55U w / Mitsubishi Diesel S4QL Eng
There are a few re-power engine distributors in the USA, so hunt around. An engine swap could be cheaper than a rebuilt from the ground up.