Based on those pictures, I'm going to say your front cab support is rotted away.

[on edit] Looks like you might be able to unscrew that added floor material. The bolt head is aft of the parking brake pedal a bit. Maybe they just covered the depression where the bolt head is.
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Last edited by klhansen; 04/05/2024 6:56 PM.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.