Cooter are you saying that the 451, a833 4speed with a 489 rear is not strong enough? This is the advice that can help me now so please elaborate a bit - my car is stripped and I have all the pieces ready to go in as soon as it comes back from paint, but if that drivetrain is weak I'd rather wait and get what I need - bear in mind I'm on a budget so brand new high dollar axles and tranny's would be nice but not really gonna happen - Maybe some cromoly pieces and ccm Ujoints like I use on my rock crawler?
First off, there is no "Magic" formula to give you the best 60 ft. time, best cruising rpm, best fuel mileage, and basically, the best of both worlds as far as gearing the rearend goes...You either want it to set the track on fire, or you want to cruise it...This is where you need to make up your mind cause the Dana 60 you will need does NOT lend itself to gear swaps as easily as that 8 3/4...In order to get ANY kind of 60 ft. out a 4 speed car, you will need to do more than worry bout the rear gear..In an auto car, you have the torque converter, first gear in trans, and the rearend gear working for you....In a 4-speed car, all you have is first gear in the trans and the rearend gear working for you...A sh*tload of trial and error traction aids will have to be implemented. No, this isn't as easy as one might think it is....Oh sure, some will try and tell you that running the 5-speed set up is the best way to go..I disagree here. We ran one of these "Tremec" 5-speeds in the Mustang for about 5 passes under full power. It was in a bucket when power shifted. They Will NOT last under brutal drag racing conditions. They are meant to TRY and give the best of both worlds, but with the super low first gear in the street version, one has the dreaded "Dumptruck" syndrome to deal with taking off from dead stops. There is another trans with a higher first gear ratio, but the Overdrive ratio is not quite as tall...Good luck...