Hi,
I've just bought the National kit plus two Numax 86ah batteries (claimed to be good for both deep cycle and cranking) and a battery tray from APB Trading.
I might get round to trying to fit them this weekend. If so, I'll post pictures.
I was warned off using the original battery due to the need run matched batteries and because the original is very large and may not fit turned round. I can see the problem with the size problem but I don't know if the compatibility thing is true or an attempt to sell more batteries.
The seat box in my TD5 has a step in the floor on the transmission side. The battery sits on the low side and the jack on the high side.
The new dual battery tray will fill this step raising the battery/s so the OEM battery may end up with the terminals above or uncomfortably close to the seat box lid.
I'm hoping to fit a compressor in the same box so I caved in and bought two batteries in the end.
One thing you might need is a heavy duty crimp tool if your going to make up your own battery, winch, acessory, jump leads. I bought a hydraulic one on ebay for £45 which works well.
Cheers,
Steve