Freedom Wolf Resources

The Freedom Wolf 80% Glock platform frame by Lone Wolf offers compatibility with gen 4/5 slides, but also requires a unique combination of parts that make it slightly more complicated.  It requires a gen 4 trigger housing, gen 4 magazine release, but a gen 3 locking block.  The frame CAN be modified to accept a gen 4 locking block, but warranty support from LW would be forfeited.

The all-in-one LPK from LWD is the easiest most cost-effective option, but is rarely in stock.

If you can't get your hands on the LWD completion parts kit, you can get it done by ordering all of the individual parts listed below it.  That's how I did mine, and it runs great.