Gidday Foz,
I'm not to sure what belt you were running on the gilmer drive, but for my money you can't beat the Gates belts.
Normally the belts you get with the Gilmer kits are pretty ordinary and as usual are made in China.
The belt you need is as follows and is manufactured in the UK.
Gates Powergrip 390L.
Available from Superoo Ford spares in Armadale ( and various other go fast places ).
Other trick is to not over tension the belt.