As seen in this rehearsal video for "On a Plain", Cobain can be seen playing his rare Mosrite Gospel with a Mk IV body. Presumably, this video dates from 1991. @ around the 2:50 mark the light catches the bridge, and you can clearly see that this is not a bridge that ever featured on a Univox Hi-Flier. Additionally, there is photo graphic evidence here, here, and here.

Also, let's look at when this guitar passed through Heritage Auctions, April 17, 2004:

"Nirvana: Kurt Cobain's 1960's Mosrite Gospel Guitar. This instrument is unusual in a couple of ways. It is the only known example of a Mark IV style Mosrite Gospel model. While Kurt owned and smashed many cheap (usually Univox) copies of Mosrite guitars during his career, this was one of only two actual Mosrites he owned. (The other was damaged and given away.) It was also one of his favorite guitars, which saved it from the usual fate of the instruments he used for live performances. Kurt purchased the guitar in San Francisco in 1990. "According to Earnie [Bailey], 'Kurt had only one Gospel, and this is a beyond rare guitar. At the time Kurt died, I was secretly working with Loretta Mosley to build Kurt a lefty Gospel... in some cool color.' Unfortunately, Kurt passed away as Earnie was gathering photos to send to Mosrite of Kurt's original. 'Loretta sent me a nice letter after it ended, as she had recently lost Semie (husband, founder of Mosrite) and was now running Mosrite on her own... she had sent me some sales literature of another Gospel, but could find no history of ever having made one based on the Mark IV guitar.'" (Quote reprinted from www.kurtsequipment.com.) Kurt had painted the very small Mosrite dot markers with white-out to make them more visible in a live setting. Although the current owner removed this simple modification, residue is still visible on the instrument. This is a factory right handed instrument, so it was modified for Kurt with a strap button added to the treble side horn, and the original metal string guide has been flipped to allow it to be strung left handed. The original case bears the words 'NIRVANA' and 'F... Elvis' [colorful expletive deleted here but preserved on the case - Ed.] in white paint which, while painted over with the same white paint, are still visible on inspection."

Wendy Bagwell is seen playing a Mosrite Gospel Mk IV guitar in the YouTube video "Wendy Bagwell and the Sunliters - Give Me Your Hand." This appearance highlights his connection to the Mosrite brand, known for its founder Semie Moseley's involvement in gospel music.