Tranny won't engage gears

[Angeldaddy]

Ok so to start I just recently finished a full engine swap with a "newer" m10 from an 84 model to an 85. The engine itself is now working beautifully after tinkering with timing and all others issues including vacuum leaks. Now after i have run it just in park for 30-45 mins then flushed the oil to insure any contaminants are removed she's ready to go. I then tried to put it in drive and take her for a spin, I just started to roll down the driveway. I pressed the gas a slight amount to get some acceleration and I get no response, i shift it into reverse and release the brake and it continues to roll forward downhill with no response. Keeping it mind this is the 3 speed not the 4 automatic. I had put royal purple tranny fluid in the tranny and torque converter untill a mechanic friend im close with strongly recomended draining it and switching to basic castrol Dex/Mec 3 fluid due to the royal purple being "too slippery". I did the swap and still no response. Im lost now, so any help would be greatly appreciated. Im not incredibly well versed with transmissions to begins with so my level of knowledge is rather limited in troubleshooting..

[thebutterson]

Double check all of your linkages and make sure they're hooked up properly.

[andrewm]

Remember, you very likely didnt get rid of the purple. You drained your transmission maybe, but that isnt near all of what is in there. If you need to remove the fluid in it's entirity you'd need to a bit more than that. You can do it by hooking up an air compressor and blowing it out, but there are risks with it

[jeffnhiscars]

I wouldnt think some left over Royal Purple would cause this. Did you check the fluid level with the car running and..I hate to ask...but did you put the drive shaft back :-)

[nando]

You need to check the level and fill with the car running and transmission in neutral. you can't fill it correctly if it's just static.