24" MTB Crankset Truvativ E300 3.0, 42/32/22 Right arm replacement? I just got a Marin 24&quot; MtB the right crank arm is about 1/2 stripped from the pedal not being fully tightened before riding.
I tried doing an internet search and I only see left crank arms.  is it possible to use a left side on the right drive side?
Not sure what the numbers mean  42/32/22 ?
I think the arm lenght is 165
I was hoping that 1256A1 would be a good part number to find the right crank arm.  I am pretty sure this is a 3 piece crank.  not definate as this is new to me.
I saw some videos on retapping the threads .. i have a tap and die set i borrowed from tool library but the videos suggest special &quot;bike crank&quot; taps.  I dont have a vise either at this point in my apartment. 
is there a safe way to get the crank arms off without a puller?    when I was young  bikes didnt need all these special tools.   wow! things change
thanks
Fitting a helicoil or thread-replacement is the correct fix, or the whole crankset needs replacing.  From your photo, the right-side crank arm and spider are one part, and it may be rivetted onto the chainrings.
Sadly, thanks to some poor historical choices, the thread of a pedal is a weird combination of 9/16&quot; diameter, and 20 TPI, where the common industry standard is 18 TPI.  Thus, the taps and coils are specialist to the bicycle industry and are therefore very expensive.   And additionally, the left-side pedal is left-hand thread, so the tap and inserts are all duplicated.
I'd bet that your tool library tap set won't have the required items unless its a specialist bike set.
Even having the 20TPI parts isn't enough - making the pedal thread bore at right angles to the bike is also critical, and the accuracy required is too much for a bench vise and a hand drill.  You'd need a vertical mill ideally, or at the very least a rigid pillar drill/drill press.

Your cheapest option might be to look for a donor bike.