Projects Gearbox and diff options

Hi everyone from New Zealand. Im new to the Hamb but ive read quite a few threads as a guest.

Ive putting 460 bbf (stroked to 472) into a 77 xc falcon (australian built). I am planning to run a wide ratio toploader gearbox which I already have. The car weighs about 3600 lbs. I should be running about 500 rwhp and similar tq numbers. The car will do the odd run down the strip and a day or two a year around a circuit but 95% of use will be on the street.

Id like some opinions/ advice on what diff ratios you guys would run with the toploader? I was thinking about 3.25 gears so the engine wouldnt rev too high on the highway. Im just worried it may be hard to get off line. Thoughts?

My other option is to sell the toploader and buy a tko600. That if i get the .68 od i could run a 3.9ish gear in the back to get off the line better but still have od for cruizing. The downside to this option is its extra $$$.

Any thoughts on these two options and diff ratios would be appreciated

 

Hey mate, an XC Falcon is off topic here .
But my advice is to throw a TKO 600 at it.
Only about 50% more expensive than a rebuilt Wide Toploader [with a higher torque rating]
Add a shifter to that and the gap gets smaller.

If you cruise at the speed limit at 2250RPM with 26" tall tyres a 4.1 ratio is what you need with a 0.68 overdrive.

 

Hey Kerry

Thanks mate I appreciate that input. Good to talk to another kiwi. I already have the toploader which is why im still considering using it. The od is tempting me tho.....