[Marky Dissod]

So http://www.pcmperformance.com/programming.html is the next best in line?

I've no experience with Bryan Herter, so I can't and won't say testify about him or his service either way, but there are very many who would reverse the order you inferred [without cause].

http://madz28.com
I dealt with Ion and will again, especially if you have a t56 tranny.

He's the only one who could have the reverse lockout solenoid work and still have AC.

1st of all, Ion no longer lists custom tuning services for anything older than 1999, so the LT1/L99/LT4 is right out.

Product Discontinuance
Wednesday, 02 October 2013
For a number of reasons (including aging components and poor vehicle maintenance), we have permanently discontinued a number of tuning and control module repair products. We will only support products currently listed on the website. We apologize for any inconveniences caused.

So sayeth Ion.

2nd of all, an ISSF member [whose handle escapes my memory] has previously testified to pcmperformance's ability to make a T56 [including its reverse lockout] work in a Roadmaster without compromising the AC; in other words, Ion is NOT the only one.

 

[Marky Dissod]

Fans programmed to work with a 160°F thermostat while the engine uses either a 180°F or a 195°F will be on CONSTANTLY until the error is corrected, either by installing the thermostat that was programmed for, or rewriting the program.
Doing so for more than a few days amounts to a torture test of the fan motors, relays, and wiring; next comes Gary's Innovative Wiring 9C1 Fan TSB Harness.

You can:

• ask Bryan to adjust the fan thresholds for the 180°F tstat after he names you his price
• find someone local with TunerCAT/TunerPro to adjust them after they name you their price
• install the 160°F tstat, so long as your winter does not involve temps below subfreezing