Yes, this company went bankrupt.
We have the following series alternatives:
400 series à MTH ; see here a summary of the 400 series part numbers
600 series à MHS ; see here a summary of the 600 series part numbers
1000 series à HHS ; see here a summary of the 1000 series part numbers
the push pull oddie fasteners we also have alternative look-alikes.
It means you utilize
1000 series: diameter 10mm
+ 
600 series: diameter 6mm
+ 
For the 1000 series you can utilize the Turnlock alternative HHS series, that has a similar diameter, so similar strength.
Since you use slotted head steel zinc plated: I recommend to use: https://www.turngrip.store/products/heavy-duty/high-strength/hhstlhs
Together with the receptacle https://www.turngrip.store/HHSRF41Z
To know what stud length you need: you’ll have to give me the panel thicknesses and the gap that might be present between the two plates.
Please give the plate thicknesses with a tolerance of 0.10mm
P = ?mm
F = ?mm
Gap = ?mm
T = total thickness
For the 600 series you can utilize the Turnlock MHS series
https://www.turngrip.store/products/medium-duty/high-strength/mhstls
Here again I would need your panel thicknesses and if there is any gap between the plates
Then I can send you a quote.
Please contact us info@turngrip.store