i found these pages usefull when screaming down the hiway and my spedo's maxed out...
http://www.corral.net/20anngt/trans.htm
not too sure if it's right though... i know the rear end ratio isn't quite right...
http://www.f-body.org/gears/
that's what i accually used to calculate it, again, something in the calculations aren't quite right, my spedo is in km and the top number is 180, and when i was at 4900 rpm (not sure if it was 3rd or 4th) my spedo was right where 200 SHOULD be by thoes calculations, i was really doing 187km/h, unless.... my stock tach, the needle was right on the the edge of the yellow, and it's damn accurate, i also have my auto gauge tach in there and they read identical till i hit like 5000 then the stock one reads lower than it should
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89 fox, mostly stock, C&L 73mm MAF, bypassed coolant hoses to egr spacer, intake silencer removal, no a/c, all options but power mirrors?? blown cats

, msd cap and rotor, bosch wires, autolite plugs, 5 inch auto gauge tach with recal and blue lensed shift light, PAPER FILTER

I BOUGHT ONE!!!!!!! felpro gasgets on everywhere accept oil pan and a nice big classic mustang decal on my back window