It sounds like mine is similar K. The inner edge of seat boards are shaped to give nearly an inch gap at the forward end dropping to less than ½ inch at the back. This appears to be a positive effort by MMC to allow greasing access and doesn't affect water intrusion as the gap is sealed by the transmission tunnel above.
Although a steel cross member is immediately below the front UJ, a gun can just be angled in from behind through the wider board gap to reach front UJ and sliding joint grease nipples.
In John's case I agree the only option is to gain access from above after removing transmission tunnel. Interested to know how much sealant is used though.
