What is the correct antifreeze for a 2001 Jaguar XK8?

I recently wanted to flush and replace my 1999 XK8 antrifreeze and found the dealers $45/gal price ludricous. After some research, I found that the "Peak Global Lifetime" product is acceptable for this car - I even asked and received Peak confirmation that this would work - Initially, I couldn't find the undiluted product locally so I called Peak again and found that Walmart carries the 50/50 dilution for a reasonable price - I took 3 gallons in for the flush and replace (at Jiffy Lube) and got one unopened back.