Look like grousers for a Thiokol 4T N ( narrow chassis). Let me get measurements for hole spacing off mine.
My 4T8 has a traction bar that is two square tubes, but the one you have would work just as well. The others
would be standard grousers.
Measured the grousers on my 4T8.
32 inches across and 1 1/4 square tube
Bolt hole spacing from end is
1st hole 1 1/2”
2nd hole 3 1/2”
3rd hole 6 1/2”
4th hole 8 3/4”
5th hole 11”
5th holes from each end are 9 3/4” apart
Note that the tire guides have rounded shoulders like the pictures from vintagebike!
I found a listing under Thiokol parts on eBay for grousers for either an Imp or a Sprite that are different length
and different tire guides.
vintagebike If you are interested in parting with those, let me know!