Thanks Pabs for your suggestions.
I couldn`t find anything in my FE/FC workshop manual about ute diffs being different to a sedan. I assume you meant the ratio is better suited to towing?. The manual says 3.89. If there`s a lower ratio I`d be interested.
Thanks again...(Yes, cool is a big priority!!)
Chow..
All FEs and FCs had 3.89 diff centres. Utes did have extra leaf-springs in the rear, which might be worth considering. The EH/HD/HR had 3.55 ratio diffs (typically in autos) and 3.36 ratios in the manuals. The 3.55 goes well with the grey motor. IMO the 3.36 puts a bit too much strain on first gear, but YMMV.
And ditto on keeping it cool.
Hope that helps,
RET