Will not shift from first to second unless letting off on gas

low tranny fluid

try checking your transmission fluid level , low fluid will cause shifting problems

Hi :) Check the wiring harness for a fuel pump relay that is on the firewall. The trans is computer controlled (shift points, firmness, ect). You would either need to run a TBI motor from a '92-95 3-4 or 1-ton truck and get the computer to go with it. Then the new gas computer can run the trans. You will also need to swap the torque converter to a gas unit instead of the diesel. OR get whatever motor you want, and then use a stand-alone controller for the trans. They cost about $600+ for the controller. Still need to do the torque converter. You could run the diesel TC but it just wouldn't perform to full potential.It will bolt up, but a diesel transmission is different from a gas transmission. Diesels shift way earlier and only go to 3500 rpm max. If yo u do the engine swap, you will need a new valve body in the transmission. I have a 700R4 in a 1935 Ford truck. It never shifted right unless I drove it manually. It always bogged down. I took the transmission to 5 different shops and no one could figure it out. After 6 years, I was telling a buddy about it and he had me bring it to his shop. He changed the valve body (was a diesel trans and I didn't know when I bought it at an auto swap) to a corvette valve body and now the truck runs great.

This is just a guess but the whistling sound you desribe suggests a vacuum leak,such as a split line.If a break is not obvious,lightly spraying the suspect line with ether with the engine running will cause the rpms to go up when you are in the area of the break.Good luck

Do you have vacuum to the modulator?

sounds like a shift selonoid inside trans

It won't shift 1-2 or 2-3 or both unless you let off? If it is just 1-2 it might be a band adjustment, but I'll bet you have a plugged governor solenoid screen also.

need a trans

sounds like trans has gone bad, last service of filter and fluid? clogged screen or low/burnt fluid would effest but if clunking sounds like trans is shot

Sounds like the 2/4 band is burnt. Does it backup?