All of the Retube Kits below are Low Output kits and these kits use the JJ EL844’s for power. These are completely different tubes than the stock tubes your Dr. Z Stangray came with. The JJ EL844’s are a proprietary tube that JJ Electronic built at the request of Eurotubes.
The dissipation of the JJ EL844 is 25% less than a standard EL84 so using the EL844’s will reduce the power a little in your amp.