Chrysler Repair: 1994 concord transmission, chrysler concord, mechanic friend

Question
i have a 1994 chrysler concord 3.3 ltr with the i think its the a606 transmission.The problems i am having are becoming more and more frequent seems the tranny tries to go into O.d its a 4 speed and then it just slips out .drives fine in 3rd gear sometimes shifts a little hard.anyway had a mechanic friend of mine retreve the codes with a snap-on code reader and i wanted to know what they mean.54/46/51/36/35.alot ha just replaced the filter and tranny fluid completely removed cooler line from rad and pumped it completely out with engine running.so this might have somthing to do with some of the codes in the computer any info would be appreciated. thanks .  

Answer
Hi Chris,
That is a large number of codes. The 35 code may have been caused by the power flush: loss of fluid pump prime due to possibly low fluid level, oil filter damage, cooler line fittings, o-rings missing on filter. You could erase the codes (disconnect the battery) and then reread them after a drive to see if the 35 is still there, but I would believe that it was set when you did the flush.
The 36  means that the 51 and 54 codes were set immediately after a shift. It generally means that there is a mechanical problem behind the 51 or 54 code (rather than an hydrualic problem).
The 46 tells that it observed what you did: a 3/4 abort and points to an internal transmission failure.
The 51 means there is some slippage in 1st gear (the ratio between the turbine and the output is not correct) which could be due to a speed sensor malfunction or an internal trans problem.
The 54 means there is slippage in 4th gear, but it can only be due to internal transmission problem.
It would appear to me, an amateur, that you indeed have a problem that is going to require a rebuild...ouch!
There are just too many signs pointing that way than toward an hydraulic or speed sensor problem.
By the way the trans at that point in time was designated as a model 42LE.
The cost of a rebuild or buying a replacement rebuild exceeds $1500 so you probably have a fork in the road here to choose between. Limp on, bite the bullet, or sell/junk the car. It is not uncommon for this to happen so don't blame yourself.
Roland