Upgrading an Alternator

Couple of thoughts;
Do you have a need for the extra current. Is there an amp meter installed and always showing high charge current?
Do you have a second V belt notch, usually anything near and over 90Amps will require a double V belt or fat serpentine belt.
Nothing is for free, it takes HP to turn a loaded 140Amp charger.

I thought the TIBs used direct drive alternators. The only replacement is the Leece Neville 3 bolt mount.

The 12SI would be a better replacement if you do have a 10SI in there now.
https://alternatorparts.com/10si-12si-high-output-alternators.html

Next on my list is the 31SI. You may just need a belt adjustment arm extension.
I really do believe your going to start spinning or tossing the single V belt though.
Are you running your A C equipment or water heater needing 140A to your inverter?
Must be low or dead (or bad) inverter batteries. Most inverters charge current can be reduced.

This Detroit Part MAY help
https://www.powerlinecomponents.com/detroit-diesel/23508421/pulley
It is a 10 groove pulley with a 7.5 inch diameter. You may need a longer crank bolt.
Also, Vintage parts ph# 877-846-8243 usually has them on the shelf for bus conversions.

the 12SIs came in different amp ratings, probably about 3 beers on line to confirm the correct part number.
It may take some work. Not many of the part counter kids may have a clue, your looking for a real fat 1/2" PTO belt. Not a fractional HP belt.
You will know it when you see it. Like a belt under your riding lawn mower.

Also, look back there next to your raw water pump. Do you have a blank gear cover plate? This is where a direct drive alternator really comes thru. Do you have an old school DD guy with used parts?

Both gear covers blank? What drives your raw water pump?

I'd like to talk more about this high amp draw. Assuming a 12Vdc system; 1680 Watts.
Is this continuous or when the fridge/ice-maker cycles?

Now your cooking. Still find some better belts, but now, you don't have to run with guitar string tight belts. A little (little) slop and they will last forever.

It's getting harder and harder to find those match sets any more. I have not found a set package in many years.
A Gate rep told me one day that the new mfg processes ensured all belts are the same.

Well Flunk on that.

I have purchased the same belt approx a short year apart (gen-set spares mgt) Both un-used, same temperature and near 1/4" different in length. Double Flunk.

I have 3 alternators on two engines. All use the same belt on double pulleys. I ordered 8 belts and a better bottle of rum and crawled into my ER.
Just over half of the rum was utilized before I matched the belts for each alternator and ended up with a real close matched spare set.
4 years later, all belts have the same deflect and perfect (matching) wear patterns.
It may take the (equivalent) rest of that rum convincing myself to replace those belts this spring.

When you pick the new belts up, check all the required belts the store has for you, on their belt measuring tool. You may be visiting a few NAPA stores before you make it back home with perfect sets.

Keep us up.

What else can we spend your money on?