The Frank Howard recordings first became linked with Hendrix via the release of the compilation cd "Old Town and Barry soul stirrers" (Cdkend111). The liner notes suggested that Jimi Hendrix would be playing on "I'm so glad":

"Another record to fall along the way was Frank Howard &
The Commanders 'I'm So Glad', licensed in from a Nashville production
company. Its belated success on the northern soul scene puts its resale
price higher today than the fee the Commanders' guitarist would have been
more than happy with then. The guitarist actually made it to the UK before
the record, and with his group, the Jimi Hendrix Experience, found success
of his own."

When asked about this track Billy Cox said that he thinks that Jimi played on it, I exchanged emails with Frank Howard during 2003 and he stated that Hendrix played rhythm guitar on both sides of the 45.

A likely time for the single's recordings to have taken place would be around July 1965. Jimi had quit Little Richard a month or two before, and appeared on the TV show "Night Train" performing "Shotgun" with Buddy & Stacey, filmed in Nashville, Tennesee. The date of the TV recordings is unknown, but on the same show Jimmy Church performs "In The Midnight Hour". The Wilson Pickett version of the song was released in early June 1965, so the TV recordings had to take place later than that, and in early August Jimi was back in NYC gigging & recording with the Isley Brothers.

Also, the Commanders appeared on the "The Beat !!!!" TV show in late 65 - early 66 performing "I'm So Glad", so the 45 had most likely been or was about to be released by early 1966.Billy Cox has said that Jimi left and returned to Nashville several times, probably for one reason or another after leaving Little Richard's band Jimi ended back in Nashville and did whatever work he could find before returning to NYC and the Isley Brothers, one of these jobs being the Frank Howard single.

Discography including releases (also including ones not featuring Hendrix):

FRANK HOWARD & Commanders:
Just like him (Robert Riley) / ? (HERMITAGE 870) 1964
I'm so glad (Billy Cox) / I'm sorry for you (Billy Cox) (BARRY 1008) 1966?

Judy / Smoky Places (EXCELLO 2291) 1967

FRANK HOWARD & Continentals:
Do what you wanna do (part I) / Do what you wanna do (part II) (DELUXE 124) 19??