Auto to 5-Spd Swap Problems-Please Help!!!

[87shawn22r]

So here's the deal. I have a 1987 pickup with a 22r. The original transmision was the A43d with a F302 rearend. I've found some gearing charts online and this tells me its a 7.5" rearend with 3.737 gears (going on memory on that one). I bought a 5spd from a junkyard.. tried to identify it but didnt have any luck. At any rate, it bolted right up. Took it out on the street and hit a top speed of 57mph. My truck was winding out so hard in 5th I thought I was gonna blow the motor. I couldn't believe it. I got a rearend from a junkyard out of an 88'2wd with a rearend code. G662 which should be a 8" with a 3.017:1 gear ratio (the donor truck originally had a 4spd manual G40 transmission). I thought this would do the trick for sure. Results: Top speed 65 max and thats really pushing it. My estimate is this. My 5th gear is probably somewhere around .85:1 and my rearend is 3.017:1. So where's the problem? With the automatic, when the overdrive worked this thing would cruise 85-90 no problem. This truck should at least go 75 i'd guess. Any sugestions please! Something else has to be going on... maybe I forgot to jump out some wiring or something.