At the time of their introduction into service, I was going out with the daughter of a WO engineer who worked with them at delivery; a woeful tale of ejection seats with hammer marks on the top where they had to hammer them onto the rails to get them to fit and large gaps between the bulkhead and the sides of the engine compartment. It may have been a Jag Shorts tried to deliver, but it was assembled by navvies.
I also heard that when they lined them up outside, they were of different lengths too.
Completed a stellar service though, so fair do's.