1999 Dodge Durango ECM/PCM shorting out

Friends,

Please help me! I have a 1999 Dodge Durango, big V8, 4x4, auto transmission, and about 116,000 miles on it.

It started having problems shifting out of 2nd gear lately and I dropped the drain pan only to find band material. I took it to a reputable transmission shop for a rebuild. They rebuilt it and took it for a test drive. They said the "lockout" solnoid was not working right and they went to start it up to pull it back in and it would not start -- no fuel pressure was the first thing they checked, but finally discovered the engine computer was bad. (They said they had already checked the "grounds" to make sure they were connected, and also checked their transmission solenoids to make sure there was not one shorted out.)

They finally got a rebuilt computer and it immediately shorted out. They towed my Durango to Superior Auto Electric here in Tulsa and Superior shorted out 2 brand new computers before he thought he got it fixed. They drove it 6 miles back toward the transmission shop and it died again, apparently shorting out the new engine computer. I have been without the Durango for 5 weeks now. They said they thought the problem was coming from the "bus" or else "CPU" which apparently is external from the computer. However, I never had any problem like this before they worked on the transmission.

1st Question - Any ideas how to get my Durango going again?

2nd Question - Should I pay for an engine computer and the related diagnosis & labor, or was this shorting out likely somehow the fault of the transmission mechanic?

Thank you!
DWL