First of all, I'd like to say that I've read a couple of the threads about this topic, and I'd like to see if I understand the fix.

I lifted my truck and had no problems running 35” tires. I had 35" tires programed in the ECM/PCM and had no issues. I recently had my truck regeared to a numerically higher ratio out of stock ranges, 4.56. After doing this, the speedo was off and the ABS light/red ”!” brake light was on. I assumed this was b/c the gear swap I’m sure this is a common problem and I wanted to know what suggestions you guys can offer. No one has been able to point me in the right direction and its getting frustrating.

From what I've read, you get a tech II to program the EBCM with the correct tire size and gear ratio, or just tire size?(this corrects the wheel sensor reading). With a handheld, you program the PCM/ECM with the correct gear ratio and tire size (this corrects the VSS). Is this correct?

A work around is just dropping the tire diameter below 34" and leaving the gear ratio at stock. The ABS light will go away, but the speedo will be off. Right?

you need to have it reprogrammed. tire size is only one issue. the tail shaft sensor is getting more signals than the wheel sensor can match to it. if these are off by more than a couple % then it throws the ABS light on because it can tell how fast to vehicle is going. basically the computer is confused. a local speed shop can fix this with EFILive or HP tuners program or if you know somebody close by with EFI even better.

Basically, if I go into a local speed shop, and tell them the problem, they will know what I'm talking about and be able to fix it?

For my own knowledge, is it the EBCM that actually needs the programming?

if they are reputable they should. the ECM definitely and you should have the transmission done also so that it know how to shift with the new gears. both are fairly easy and shouldn't take more than an hour for both, probably less but charge will be for an hour. The BCM doesnt control the TCM/ECM.