Its possible it wont be strong enough to hold the HAN boom in which case I will double them up. The best part about these accuators is that they feature the motor as well as the accuator so its not as expensive as it seems.
Ill let you know how it goes. I hated that I couldn't leave the 8421 "on display", and I lack the ability to create a decent working version of opposed LA's.
I know it seems like I am repeating myself but trust me when I say I have spent the last 3 years looking for an acceptible solution. The Firgelli accuator works very very well for the price since it includes the motor built into such a compact size. Theres another guy thats posted on EB before that made all metal accuators that were designed to connect to Medium and XL motors but hes gone MIA in the last few months.
If there is a strong enough desire for me to build the 8421 with this accuator to show everyone then just voice your opinion and I will get it going so we have a comparison to Alasdair's solution.
I originally purchased the actuators to use on Jennifer Clarkes Baldwin crane which originally used a "lead-screw" which was completely bespoke.