put a rebuilt 1992 700r into my 1973 z28. I've got park, reverse, neutral, and 1st gear ONLY. if I run it up to about 3000rpm in drive (not full throttle) it acts like it jumping into neutral ! will come back to 1st after the RPMs go down for a second or 2. fluid is full, filter is in place. governor is fine, detent cable set right. shifter has not been altered so I cannot pull it back into 1st, so the shifter will only pull back to 2nd. No Way will it shift into 2nd gear. this swap is getting old in a hurry ! Help !