Ditch witch chain info

Hello All
I have an old 2300 ditch witch with 2" chain with 4-pitch links set up for the standard 4" width trench. There are 17 teeth on the chain. I want to widen the trenches to 12". Ditch witch make tooth spacers that go up to 16". From what I have seen on google images some chains appear to have three full 12" wide spacers preceded by three 8" or 10" wide spacers. Does anyone know the correct configuration for the spacers? Is there a recommended arrangement for the teeth when going to the tooth spacers?
Should it be something like four sets of the following
Left tooth mounted internal
Right tooth mounted internal
Left tooth mounted external
Right tooth mounted external
Left and right tooth mounted on 8" spacer
Left and right tooth mounted on 12" spacer

Regards

Phil

my Vermeer is set up for 18 inch trench,, it starts with a tooth on the chain and pyramids out from there.
set up like this
t
t t
t t
t t
t t
t
t t
t t

try again

t
t....t
t.........t
t............t

Thank you catman13. Does it leave a relatively smooth floor in the trench?

I set a 4010 I had to 12 inches once. More dirt than it would handle at 3.5 foot deep but my boom offset behind one wheel. They say 10 horsepower per inch width of chain is the standard.

it leaves a smooth floor . you get some crumbs falling in . if you dont want some crumbs fab a crumb shoe problem solved