Nissan Repair: wont go in reverse, brick wall, loud noise

Question
My 2000 Frontier (V6) got stuck in some deep sand about 3 weeks ago.  When we got it out it wouldn't go forward or backwards.  We found that the transmission fluid was low, so we filled that up and it eventually started working ok.  however, in the past few weeks, it hasn't been working as it should. occasionally, it will go up to 4k rpm before shifting from 1st to 2nd (automatic trans.) and it makes a loud noise sometime when shifting into reverse.  This morning, I started it up and it won't go in reverse. Meaning, I can shift it to reverse but nothing happens when I hit the gas.  Also, I tried putting it in neutral and pushing it backwards but it won't move. It seems that it will go forward but I can't be sure as there is a brick wall approx. 2 ft. from the front bumper. Did sand get in somewhere possibly?  Any ideas?  Thanks in advance.

Answer
Hi Michael -

The trans probably got whined out when stuck in the sand, all the bands are most likely shot.

I have, in the past have had extreme success with a product called AT-205. Here in Hawaii, it is sold by Carquest. Excellent product. It has save a lot of my clients from trans overhauls, has cured no shift conditions, or delayed shifting.

My only suggestion is to replace the oil and filter, add the additive, and if it still gives you problems, then an overhaul is in your future.

Hope this helps -
aloha
calvin