[Kalun D]

IMHO you don't need any gussets except maybe at the front where the longest tube connects to the front threaded tube for the front rod end. If you were to move that connection further inboard you wouldn't even need a gusset there.

The loads on the upper arm are considerably less than the lower, just look at ball joint sizes on road cars. The rear leg is at such an angle that the weld contact area cross section is much larger than a 90deg. connection or a cross section of the tube. The front leg also has a large cross section at the rear weld so a gusset at it's rear isn't necessary either.

I assume this is 4130N in which case for an optimum job it should be normalized after weld, the HAZ becomes embrittled if this isn't done.