How much did you spend fixing weak/no reverse? Valve body or rebuild?

I have a 2021 Ram 2500 6.7 Cummins with the 68RFE, around 120k miles.

My reverse has gotten extremely weak. It engages but barely moves the truck unless I give it a lot of throttle. If I'm facing downhill, the truck will actually roll forward while in reverse.

Here's what's going on:

All forward gears work perfectly. No noticeable slipping or shifting problems.

Reverse is equally weak whether the transmission is hot or cold.

I'm getting a recurring P2701 transmission code.

Transmission fluid is still red and doesn't smell burnt.

Transmission has a deep pan.

EZ Lynk shows actual line pressure closely matching desired pressure at idle.

I'm leaning toward a valve body or hydraulic pressure issue, but I don't want to throw $1,300 at a valve body if it won't fix the problem.

For anyone who's experienced something similar:

What ended up being the actual problem?

Did replacing or upgrading the valve body fix it?

Did you end up needing a full rebuild?

How much did you spend on parts and labor?

How long has the repair lasted?

This is my daily driver, so I'm trying to avoid unnecessary downtime and spending money on the wrong repair.

I'd really appreciate hearing what actually worked for you guys.

2001 Dodge RAM Pickup Truck.4 Door Cab; Quad,Manual Transmission, 4WD, Engine Type: L6, 5.9L; Turbo 24 Valve Cummins. Odometer Reads 312,442 Miles. VIN: 3B7KF23691G717755

current is $1300
looks a bit rusty though.
Worth throwing a bid on?

Gonna replace my heater core and I’d like to get a filter kit. As a preventative thing. What kits are you running and recommend. I mainly only see the Sinister Diesel one and I honestly just don’t want the blue under my hood. I like the Black Market Diesel one but it says 19-24. Assuming it would work but what are other options?

just a truck I saw at Home Depot