US duplex tanks have a swim speed of 2 and British duplex tanks have a swim speed of 4. British seem to be in error.
German schwimwagen should be swim speed of 3 or 4 depending on source, not 2.
Encyclopedia of weapons of ww2 by Chris Bishop gives the Japanese unit 15 type 2 ka mi 9.65 kph in water or 3, game has 4.
It also gives weasel 6.4 kph in water so 2, game has 4.
http://afvdb.50megs.com/usa/index.html
Gives these speeds for LVTs in kph. The land and water hex speeds are at the end of the line.
LVT 1 road 19 swim 9.8 6 3
LVT 2 road 30 swim 12 10 4
LVT 3 road 27 swim 10 9 3
LVT 4 road 30 swim 12 10 4
LVT 5 road 48 swim 11 16 3
Most game LVTs have these speeds but a few don't. they are,
USMC OOB , I assumed round down
Units 21, 23, and 423 all LVT 1s have 16 4 should be 6 3.
Units 111, 299, 300 and 378 all LVT 1s have 7 3 should be 6 3.
Units 16, 17, 243, 288, 379 and 382 all LVT 2s have 11 4 should be 10 4.
Units 19, 22, 114, 206 and 210 all LVT 4s have 11 4 should be 10 4.
Unit 207 LVT 5 has 12 4 should be 16 3.
USA OOB
Units 552 and 553 both LVT 1s have 7 3 should be 6 3.
Unit 555 a LVT 2 have 11 4 should be 10 4.
Units 29 and 720 both LVT 4s have 11 4 should be 10 4.
Im not sure US army actually used LVTs even when serving in the pacific.
British OOB
Unit 710 Buffalo II/LVT 2 has 11 4 should be 10 4.
Units 58, 306, 318 Buffalo IV/LVT 4s has 11 4 should be 10 4.