[volt-nuts] Affordable batteries for Fluke 732A DC Reference Standard?

[Greg Burnett]

Re: Fluke p/n 739961 6V 4.5AH lead-acid batteries for Fluke 732A DC 
Reference Standard

Does anyone know of an affordable substitute for these batteries? Fluke's 
web site doesn't even recognize their own part number for these batteries, 
but Newark lists them at $67.49 each. The unit uses qty 4, so at Newark's 
price a set of four would cost $269.96!

According to Newark their physical size is 70x45x107mm.

The old set that were in my 732A are marked, "PT56 6V 5AH Made in China". So 
someone installed these as substitutes. I searched the internet for "PT56" 
but didn't see anything linking that number to a standard or generic 
battery.

Thanks,
Greg