Using McLeod bolt-on (1300 series) HTOB now.
3 years and 4000 miles running with no problem at all.
Mounted to a McLeod clutch, big input Toploader (1-3/8") and BBF.
https://www.mcleodracing.com/1300-series-bearing-/p104
Note:
Old 1st generation units were problematic.
The current redesigned model appears to be reliable.
McLeod provides a few spacers to properly shim the HTOB.
I took a measurement and had a single shim machined
as opposed to a stack of smaller ones to get the proper spacing.
1400 series is the slip-on variant.
McLeod has HTOB rebuild kits available.
Replacement components at Summit Racing:
https://www.summitracing.com/search/...ent-components
How to rebuild video here:
https://www.youtube.com/watch?v=K39CNwrTv2o