NGKs are very good. I like Autolite Xtreme Start Iridium plugs when I can find them. Easy starting with tiny electrodes. Not at all big on Champions or regular Autolites. The chart is very good though, to know what the part numbers interchange with, thanks.
XL-500 (One owner, me), Another XL-500 XL-15, Big Red, John Deere 350CS(Yellow SXLAO) Old Blue (SXLAO) XL-BC4 Brush Cutter, Little Red, XL2, XLA115/1/400-1P (115VAC, Single Phase, 400Hz, 125Watts) XL-98 Multi Purpose Saw 1969 T50 Chev Fire Truck 1962 K10 Chev Pickup 400SBC TH400 1981 C10 Chev Pickup 250-6 4spd 2009 C4500 Chev Kodiak Ambulance 6.0 LMM Duramax
The reference was taken out of the Homelite training manual. I agree Champion plugs the quality has dropped considerably from the old days. Here's a plug I keep around just to remind me, and this plug was brand new.