Recommend new EL84 tubes

You might try Upscale Audio as they rep Manley gear and they also sell tubes.

Think the early Stingray amps came with EI (Yugoslavia) EL84's.

They have not been produced for years, but Upscale has them in stock.

I used the EI's in a Pilot 232 power amp and a single ended Magnavox amp with good results (sound was similar to Philips/Holland EL84's).

I also used old Russian 7189 types (later marketed by Sovtek as the EL84M).

They were not as 3D, but I still liked them in the Pilot.

However, the Pilot uses gobs of negative feedback (unlike the Stingray).

Maybe old production Amerex/Holland if they want to splurge on the input tubes.

Not familiar with the driver tubes.

DeKay

Andy at Vintage Tube in Michigan and Brent Jesse should both be able to help. Best wishes on your journey to help your friend ;-)

Jim

I replaced the stock Sovtek EL84's in my Leben CS-300xs with Tungsram's that I picked up from Upscale Audio.  Nice upgrade.

I'm going to try Gold Lion next in my amp. 

@dekay I also used old Russian 7189 types (later marketed by Sovtek as the EL84M). They were not as 3D, but I still liked them in the Pilot.

Similar experience here with 7189/EL84M.  They were a little softer, not as deep of a sound stage or detailed as other NOS EL84s, but still very nice. I liked them. 

Like others here, I also tried the Tungsram EL84, and it was bit more detailed, and airy, yet not as smooth as the Sovtek EL84M military tube. Pick your flavor. Same with the Tungsram 12AU7, 12AT7s, detailed, not as smooth as PSVANE, or NOS Mullards hoarded away.