Erik,
No recommendation is implied but the ELT Tom mentioned is an ACK EO-1,
dim. 7.75x2.75x2.75 inches with a little careful prep.; it fits well on
my 1985 20B and was use on Toms old ASW20B as well but you must set it
aft & clear of the spoiler rod/arm! The Flap and Aileron control
pushrods run over the top of this model installed ELT with some room to
spare. As UH mentioned only a small ELT will fit in this location, I
don't know if the height of the shelf varies slightly from ship to ship
and or model to model, but it may so beware. The ELT mounting location
Tim mentions, UH recommends and was used on one of our BFSS club
members ASW19s is well out of harms way.
Best regards,
Rick Culbertson - 21