Can any one tell me what the difference is between a GZ34/5AR5 and A GZ34/5AR4., I am assuming the 5 tests the same as a 4, but i am not 100% sure.

any input will help
Thanks Bill

I've never heard of this # before but I googled a Chinese tube that has both 5Z3-5AR5 # so I guess it would test the same. Can you post a pic of this tube?http://www.eckind.com/product_4812134_shuguang-5z3p-5ar5-5u4g.htm

I just came upon a pair of these, both Mullards, there are some for sale on the web, but I could not find much info on them either, they look like a standard Mullard 5ar4 except they are slightly taller and fatter, as far as posting pictures, I have tried this in the past and had no luck on this site, I send pictures all the time, but can't get thru this complicated process

I don't believe that a 5ar5/gz34 exists. Almost Every reference to one, that I found on the web, is either an obvious typo, or copied from a page with an obvious typo. The page that Lou references has printed in the listing "5AR5" but the tube in the accompanying picture is silk-screened "5AR4". Some other articles have copied that listing verbiage, without the picture.

An AR5 is a power pentode, not a rectifier. Did they make a 5 volt heater version? Maybe, but I haven't seen one.