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Feb 10, 2006
S.E. QLD Australia
G'day all,

just found this forum and unsure of protocol, so thought I'd introduce myself and pose a few starter questions:

I'm an Aussie living in the Top End of Oz, about 300kms SE of Darwin.
Vehicle is a 1983 FJ60 with a self-installed GM 6.2 NA diesel. Engine conversion was carried out 5 years/80,000kms ago and I'm still very happy with it. I used the FJ60 PS and AC, and a Toyota vac pump/alt. My conversion utilises the Toyota clutch by way of an extended flywheel bolted to the GM flex plate.

Obviously my Tojo differs from US market vehicles. It's RHD and our 'cruisers came standard with 4.11 diffs. Mine is a 5-speed G-pak with air.

Haven't done anything too radical, in fact I tossed the large wheels and have reverted back to the factory chrome rims with 235/85-16" tyres.

I have a cargo barrier, bullbar, rear deck, Glynd hot water shower , twin batteries and cruise control.


1. How do I upload an avatar ?

2. Reading some posts on engine conversions.....what is an SBC engine ?

3a. What is the best diff ratio to drop cruise RPMs ? The 4.11 is too low and I don't do much heavy 4WDing. I rarely use 1st gear in high range.

3b. Is 3.7 enough ?

3c. I can also get expensive 3.54:1 (?) CW&P sets. Do you think the 6.2 has the torque to pull such a tall diff, and will it result in better highway milage ? My calcs show that a T700 locked up in top with 4.11 diffs will give the same RPM at 65mph as the standard transmission with 3.54 diffs, but I think I prefer the manual gearbox.

Thanks for any advice. Look forward to many conversations.
3.70s are only 10% higher than the 4.10s you have - they're real plentiful in the US (I have a couple of extra diffs with 'em). You didn't say why you did away with the rubber overdrive - that's the cheapest & easiest way to raise your ratios.
Sorry, the 'big' tyres were only wider (15"dia) and actually smaller rolling diameter than the factory jobs.

I figure I'd like to go as tall as possible with the diff to get down around 2000RPM @ 65MPH. This will be great for highway, and be sufficiently tall enough that I can pull a big load in 4th if need be. As it is, 4th is too low and 5th is often slightly too tall for pulling a car trailer or caravan. I'd much prefer to pull in 4th anyway, as I believe 5th is actaully quite weak on these first generation 5-speed tranny's.
google grimms calculator and find the site.....

lets you pick a combo of tire sizes, tranny,tcase blah blah then gives your highway speeds and tach numbers....
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