8/4 ohm OT for DRRI?

Anybody modded their DRRI or otherwise deluxe reverb with an aftermarket OT with 8/4 ohm taps? If so can you recommend an OT? I find the DRRI to be a sort of "almost there" amp w.r.t. headroom, and I like the idea of being able to use an extension cab, but this seems practically impossible with only an 8 ohm output...

Classictone 40-18038 looks pretty good and the price is good. Haven't checked the dimensions yet though.. Any other suggestions?

Any decent 20-30W PP OT with a ~6k6 reflected load should work fine.

However, the extn cab will work fine plugged into the extn cab socket on your standard DRRI

Maybe an Allen Amplification TO26?
I copied this from their web site:

NEW! A beefier output transformer with 50% more core steel for Deluxe™, Deluxe Reverb™ and similar 2x6V6 based amps bolts right in with the standard 3-1/8" mounting centers (fits a Princeton™, too!) and has both 8 and 16 ohm taps for single and dual 8 ohm speaker configurations. Custom wound exclusively for Allen Amplification and made in the USA by Heyboer this unit features a special high performance core steel for maximum output and clean bass. 7,000 ohm primary to 8 or 16 ohms. Also works great with a 2x6L6 or 2xEL34 amp (with 4 or 8 ohm speaker load) where the intention is to limit the output with core saturation for natural compression and sustain. Low profile "fat" design to clear the speaker in combo amps. Excellent choice for 18W Marshall and similar 2xEL84 amps, too. Paper tube, paper-layered and specially interleaved windings, cool black oxide finish and 12" pretinned Unistrand leads for fast installation. Stainless-steel mounting hardware is included! 2-1/4"H by 2-1/2"W and 1.6lbs.

I am in the middle of a Deluxe build, and have the Heyboer OT that was supplied with the parts kit bolted to the chassis. Recently I realized that the Hammond 1600 series that I have would allow multiple output options. Rated at 20 watts, but it is huge! Probably a lot cleaner sound at higher volume, and need to drill a few more holes.
You really won't have any problems running another cab with your existing OT. I don't think Leo would have added another jack if it was going to hurt the amp.