It is L24 and I use a Jeans needle (90?) and standard Drima thread - it works OK and I have yet to have issues.
The recommended Ball point needles tended to bend or break on the thicker seams...
Be aware that Ventile is VERY needle resistant and thick seams - and some of my pocket tops, with pleats combining with edges and hems, plus hemmed inner reinforcing, run to 16 layers of fabric - are brutal ... some machines will not cope with this. Even my Toyota Jeans struggles and tensions need watching to avoid skipped stitches and thread breaks. I found cotton thread or even core spun poly cotton struggled to survive well - pure polyester was the only survivor and it was with extra strong poly cotton that needles tended to die...