Take an ice pick to the bottoms of the columns to see how bad the rot is before you cut them off. West System Epoxy might be your friend here- designed for wooden boat repair, I've used it for all kinds of wood repair projects and last summer for the bottoms of the turned 6x6 porch columns when we fixed the porch.

Check out their info- its pretty hardcore stuff, not inexpensive.

A detail I added after the floor was replaced (T&G D fir, painted top, bottom and sides) was to run a saw underneath the overhang to make a drip and then coated the rounded over ends and the drip with West Systems to seal the end grain before we finished painting the floor.

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95 E300D gave away
77 300D, 227k, station car
83 300CD 370k, body gone away to the rust gods, engine is in a Yota pickup, going strong
89 190E 2.6- 335k, no more
79 VW FI Bus- 154k summer driver
59 VW Beetle ragtop- 175k
12 VW Jetta- 250k
74 MG Midget-78k