Here is a teardown video of a Mini Cheetah Actuator from AliExpress.
Actuator: https://www.aliexpress.com/item/32985671853.html?spm=a2g0o.productlist.0.0.1d84249alSOOpc&algo_pvid=466b19b1-11c4-470a-868e-0c3d3f3c48a2&algo_expid=466b19b1-11c4-470a-868e-0c3d3f3c48a2-3&btsid=0ab6fa8115947737931131679e347e&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_
JST-GH Connector: https://smile.amazon.com/Connectors-Sides-200mm-length-Wires/dp/B01IZWPZJ0/ref=sr_1_8?dchild=1&keywords=jst+gh&qid=1594751696&sr=8-8
XT30U Connector: https://smile.amazon.com/Finware-Upgrade-Female-Connectors-Battery/dp/B074S7NH3H/ref=sr_1_3?dchild=1&keywords=xt30+connector&qid=1594751761&sr=8-3
51146 3 Pin Connector: https://bit.ly/32h6Hpb
MIT Mini Cheetah Video: https://www.youtube.com/watch?v=xNeZWP5Mx9s