Lull 644-TT-34 Highlander 2: Front/Rear Brake Caliber Issues

Dear Members,
I found this forum while searching for replacement Brake Caliber Assembly's for my Lull 644 Highlander 2. The issue is she will not make it 50' without the Front and Rear Drivetrain Brake Caliber's clamping down on her..
I was literally driving her 200 yds from our warehouse to a mechanic shop when she got stuck on the Highway! hahaha. It took me a hour tugging her with my pickup to get her off the street.
The mechanic( just a regular fleet diesel mechanic) tells us we need to buy replacement Caliber Assemblies for the Front and Rear Brakes. OUCH.. According to J&G Parts this part/assembly is P19145 and costs $2,614.33.

Does anyone know if the front drive train caliber assembly P19145 is the same as the rear caliber assembly? The manual shows the pads for the front are part #5 and the pads for the rear assembly are parts # 11.... The J&G Parts guy had no idea if the Assemblies were different?!

Is there a simple fix for this issue that doesn't require buying two new Caliber Assemblies?(Front and Rear)
Any Used Part Stores?
Alternate Caliber's that match up- that are easily located?
A rebuild kit of any sort?

HEEELLPPP

JLG service manuals online are an open free book for the 844. Search for it on your model.
When I called about parts they sent me the parts break downs. I dealt with an outfit in PA? but my parts shipped out of the Atlanta area.
Problem is likely tied into a safety lock out, solenoid or o-rings on a spool valve. Calibers are likely operated on hydraulic fluid unlike what most people thank about brake systems.

Don't think you need calipers. Is the brake valve in the floor? make sure the rubber boot isn't torn and the cap that the roller on the pedal itself pushes down into the brake valve isn't hung up in the applied position It can hang up and the pedal will come back up and you won't see it stuck down. You may spray it with penetrating oil and bump it with a hammer or twist it with Chanellocks and get it to rotate and turn loose. I'd check that first because it makes no sense that both ends are locking up from bad calipers.