95 transmission

[me4smoke]

Looking for reliable info: I have a 95 bird with the 4.6. I have the torgue conv. problem that I believe every bird of this year had. I changed the fluid from mercron III to mercron V three years ago. It helped for a while but it's back to shuttering. A transmission shop wants $1500.00 to rebuild it. Would it be better to get a re-built/manufactured trans. to install myself?
I also let the car sit for a couple of years. I'm driving it again and some things no longer work correctly. The odometer no longer works nor does the trip odometer and the speed odometer sometimes sticks at any speed. Is it electronic or mechanical?
The air bag light blinks 3 pause 4 code. I don't know what that means but if I shut down and re-start the blinking usually stops.
If anyone knows any answer to these problems. I've love to know. Thanks