I had a MTD 21" 5hp that had the bar blade on it back when I first started up as a Lawnie (backup mower). Actually asides from the size, the base looks very similar to mine, except I needed an ocky strap to keep the height selector from slipping and leaving crop circles in clients lawns. After a while the ocky strap broke from the sun exposure so I just stuck a stick or screwby in the gap and it worked a treat.
I found it always gave a nice cut with the bar blades, but I quickly worked out it was best to use it for level yards without rocky patches, or slashing through thicker stuff.
Was a great mower for my needs. I ended up swapping the engine off to another base for a friend when I bought my new Honda mower, as I prefer 4 blade swing-backs for what I do.
