Make sure a shop does a complete diagnostic test to be certain it is actually the valve body assembly (valve body/solenoid pack/TRS-MVLPS) and not something electrical or internal.
A good diagnosis means more than just pulling the transmission-specific codes with a scanner. Diagnostic tests include a road test, pressure checks on the transmission's side taps, and pulling the pan for a debris check. As I recall reading in the FSM, other diagnostic checks can also be done with the pan and valve body off using an air pressure test plate, and of course they can inspect the valve body internal parts if they disassemble it. You might be a little upset if they put in a new valve body assembly for over $600 and you've still got internal trans problems.
As far as pricing, the Mopar 42LE rebuilt valve body assembly comes complete with a new solenoid pack, a new filter and gasket, and I think a new transmission range sensor (TRS) (or the similar Manual Valve Lever Postion Sensor [MVLPS] in early 1st Gen transmissions). A shop could buy it at their shop discount from a local Mopar dealer (or other reman sources) for ~$275, and they'll add their percentage parts charge on to that. Putting it in is not hard on a lift for a pro, but remember part of your labor charge is for the fluid flush/fill and filter change [~$100]). If it is just the solenoid pack that needs to be replaced, that is around $150 for the shop to buy. If it is just the TRS or MVLPS (depending on year) that is around $50. (Again add shop parts mark-up to that, and of course the $200-$350 in labor for the diagnosis, install, and new fluid/filter).
Putting in a replacement valve body assembly on your back with the car on jack stands is a pain unless you are a fairly skilled, careful home mechanic and don't mind getting smelly red transmission fluid dripped on your face, hair, arms, and on your (old!) clothes. (Obviously, you also need to wear safety glasses.) Nevertheless, there are a few How Tos and threads here and on LHforums dot net on this. Beware that it is tricky to get it out and especially to put in back in. Two people make things much easier. Do a search on the threads on "valve body" and "solenoid pack" and you'll get all the details, rather than me trying to go through it all. The FSM and most of the manuals don't describe the procedure very well.
Be warned that if you drop the loose round accumulators and they are dinged up or scratched, you've got to order new ones. If you drop or otherwise damage the new valve body assembly parts, well that's up to $300 that you just as well could have spent on lottery tickets.
BTW, the valve body check balls won't fall out unless you disassemble the valve body, which should NOT be done except by a trained transmission tech. You need a couple of special tools anyway, so don't try it. However, If you are skilled enough to take the valve body assembly out, you can replace the solenoid pack and the TRS (or MVLPS). Both of them are just held in place on the valve body with screws. The pdf of the Factory Service Manual archived on this site shows the procedure.
You also have to keep the new valve body and the underside CLEAN. E.g. you can't have the valve body sitting there while you are scraping off gasket material. You should do this in a clean garage or covered carport with a smooth, dust free floor (clean it first) - not in all the dust on the street. Avoid touching the new valve body with dirty hands (use clean nitrile gloves). Anything you wipe on the underside of the transmission (for example if you get scraped gasket material stuck there) must be wiped with special lint free towels, not shop towels. Some parts stores or specialty auto paint stores have them, but they are hard to find. Alot of tiny debris (like grains of sand blown into the underside while you are working) can clog up the fine passages in the transmission and valve body and can cause other problems if they circulate around the transmission before the filter catches them.
All that said, for most people, paying the ~$300-$350 labor in addition to your parts cost to have the shop do it is well worth it. If things go wrong doing it yourself, you'd have to tow the car to a shop and explain what you did. (Real bummer.)
To find a shop, if you don't use a Dodge/Chrysler dealer (more expensive), I'd recommend an ATRA member shop (Automatic Transmission Rebuilders Association - searchable on-line at ATRA dot com).
Last edited by pt500; 05-17-2012 at 05:07 AM.
Reason: clarify & check ball info