Fresh rebuilt 700r4 drove 2000km now no forward gears
I have a 1991 c1500 with a fresh rebuilt 700r4 tranny +shift kit.
It was recently parked for about 7 months, so I got it up and running again drove it for about 500km with no problem, yesterday I put plates on it went to leave my house and have no forward gears. Reverse works 100% fine but when put into drive or first it just sits like its in neutral and when applying pressure to the gas it just revs and doesnt move. I am really hoping my transmission is fine as I just spent 2600 on it last year..could it be another component? I'm kinda tight on cash right now and my neighbour works for an engine rebuilding company and knows a little about trans but not much.. any ideas on where to start looking before we pull the thing right out? I got under then truck to see if there were any visible telltale signs and I noticed this area is covered in oil and I don't know why..
Thanks in advance..