please help

[TheSunDanceKid]

so i just bought a 89 blazer a few weeks ago and last week i shifted it in to 4wheel drive worked fine just played in a little mud but when i tryed to get it back to 2wheel drive it was a pain i messed with it for a while and it got out everything was fine for like 2days and now every time i get to around 40mph it acts like its in neutral and just reves then when it goes under 40 its fine this only happends in drive and over drive, drive 2 works fine and i drove it home in that and today i thought maybe if i tryed to put it in 4wheel again maybe that would fix it so i got in 4 then took it out and it did the reving **** again only at like 25mph so i tryed once more into 4 then back to 2 and it went back to only going up to 40mph so i dunno and i know the transmission was replaced in feb so that should be fine it was alittle low on fluid so i filled that up

 

[spearchucker]

Your tranny may have sucked up water when you went mudding. If the fluid on the dipstick looks milky or black, then change the fluid to see if that helps. Since it was low on fluid you may have also burned the clutches . Remove the drain pan and look for any material in the bottom. And while the pan is off change the filter.
Do you have a tranny cooler installed? If not get the largest one possible, 700r4s hate the heat.

 

[TheSunDanceKid]

well im taking it to get fluid and filter changed tomarrow but i really couldnt check the fluid because it wasnt even up to the dipstick so i added 2-1/2 qorts of dekron 3 but then i noticed it said dekron 2 on the dipstick but i had allready put it in which made it run to 40pmh and do it when before it was doing itt around 30mph so i was also wondering if putting the dekron 3 in instead of the 2 would make that much of a difference ive only ran it about 10miles total sence i added it and it will be flushed out tomarrow

and also before when it was runing fine it would slip a bit when i was reversing and since the fluid was added it works perfectly