Odd SizeToilet Seat????

I have an 25 year old toilet, the name is URC and I am trying to find a seat that fits the toilet. The toilet measures 17" from the center of the bolt holes to the front of the bowl.

I know this may sound unusual as the round seat is 16 1/2" and the elongated is 18 1/2". The holes on my toilet are 5 1/2" apart. I have measured correctly (I am a carpenter, I do it for a living). An American Standard seat sits 1/2" back from the front of the bowl and wants to slide off to the side of the bowl.

Please Help

Seems like there used to be an odd Briggs toilet back in those days.....

You may find it easier to replace the toilet than the seat. Not what you wanted to hear i'll bet. Would new seat bolts help or is the seat just worn out?

The seat is plastic and probably the original. Wife wants new seat, now she gets new toilet. Thanks for the replies.