Hi Gunny,
The ammo boxes are 17prd and 95mm from Accurate Armour and the pallets are from them also.
The .50 cal boxes on top are from the Italeri accessories kit and the rope from Billings Boat Accessories.
Here's a link to some DUKWs that I've been building which depending on sea area available might end up coming in behind the LCMs etc. 
https://armorama.kitmaker.net/forums/77072&page=1 Here's the second picture that I took but couldn't get it organised in the first post. 
 
 I was thinking about putting them at the back of the LCM two either side, I've still one to build holding stores and medical boxes etc.
I've started work on the M7 Priest which will be the main passenger but as always with Shermans it's not a straight forward build.
Glad you enjoyed them.
Cheers
Al