97 2.3 automatic, As stated removed the housing to replace the driveshaft bushing and gasket between housing and case and while I had it off the parking pawl arm and spring had fell out into some speedy dry I had under the truck and I did not notice. Did not realize until I test drove and stopped on a slight incline and put in park and yep, it rolled. Stuff happens, but also now when in reverse and drive it slips real bad. It works fine in manual low and 2nd. So my question is did I do something to cause this or is it just pure luck.

 

If you lost fluid during the gasket change, did you check the level after completing the work. First thing to check when slippage is noted is the fluid level. Most techs will suggest checking the level before doing anything else. Did you check?
The parking pawl just fits in between teeth on a 'gear' attached to the output shaft when the selector lever is moved to the Park position. To my knowledge, it does nothing else.
It does ride on a shaft poked into the back of the case. Dunno if that shaft can come out if the pawl is not installed before replacing the tail housing, and what would happen if it did.
The pawl is moved by the selector lever which also moved the spools in the valve body. If the pawl acted as a 'limiter' to keep the spool from traveling too far, then the spool may have moved to where it should not be for normal operation, out of place.
If the transmission worked fine 'yesterday', and you did this stuff to it, and now it is brucken, then un-do the stuff. Remove the tail housing and pan, diddle & fiddle the pawl back in place, and make sure the selector lever is connected properly to the spool, and within normal 'travel' range. PBT_ put back together - fill with the correct fluid and amount, and check for operation.
tom