i recently bought an unused forge actuator off ebay, i bought it cheap, simply because the seller didnt advertise it well. The thing is it was for a diesel. beh, easy i thought, i will use the bracket from my old oem actuator and just extend the rod, piss easy...
when i took the actuator apart i soon realised... sh!t, this thing works on negative pressure.. how can i fix this?..
i thought, right, easy, i will just swap the spring to the other side of the piston... good idea, but the slot the other side of the piston was marginally too small for the spring.. luckily i had a plan.. i know someone with a lathe

.... one day later and the piston is returned with the piston machined and the sping fits perfect. i put the actuator back together and it now works on positive pressue

.. a brand new forge actuator for £60.

it goes to show, you dont have to buy stuff off the shelf if you are prepared to have a go at making things work..