Does your 3t40 slip in reverse?

[ifixalot]

If I press the gas a little hard in drive, my tires squeal but if I'm in reverse I can feel a slipping in the trans.
If I try to back a trailer up an inclined driveway, it won't go, the trans slips.
I have no crud in the pan. I've replaced the reverse boost valve. I installed a Trans-Go
kit which is suppose to eliminate the reverse slip but it hasn't helped.
Everything else works just fine and my fluid is red.
I have engine braking in 2nd and 1st.
The van backs up fine, it just does this in reverse under load.
Maybe that's just the way it is with this trans?

[LMP]

..gear ratio in reverse is somewhere similar to the forward 2nd gear..much less torque than 1st gear.

IN addition, stumping the throttle going forward removes weight on the front wheels because of the direction of torque. ON the opposite, stumping the throttle in reverse adds weight on the front wheels inhibating the tendency to spin them....no surprise then when added to 1st consideration.

ALl of this (in reverse under heavy load) will load the torque converter possibly to stall condition : in this case the engine RPM stalls at some point .....a real transmission slip would let the engine RPM go up...and would fry the transmission clutches, not a good idea.

[ifixalot]

Thanks for the reply and the info.
Since I last posted, I was able to test drive a similar van and this is not normal.
When I backed up van I test drove, hitting the gas it just went backward instantly
where as mine I feel the slip. Yes if I continued to press down on the gas I'm sure the engine would rev and I'd being doing bad things to my trans.
The first time I noticed this, I was towing a 6x8' U-haul for my daughter. Backing up her driveway of about 10-15 degrees, I had to get a running start to get it all the way up the driveway.
The second time I noticed it. I was trying to back up a 20 degree slope with just the empty van. It would not back up. Again if I was to push the pedal harder, I'm sure my engine would have revved higher but I didn't want to push it.
I added Lucas trans fix and it hasn't helped so far.
I'm thinking it needs a rebuild.