Full replication of Huggett & Ventura (2000) - Understanding why high income households save more than low income households
You can find the replication codes and pdf summary here.
Basic takeaway is that everything replicates cleanly, only minor quantitative differences.
OLG has two endogenous states, second of which is experienceassetz (or ze), and one or both of a markov and i.i.d. shocks. The experienceassetz is used to track lifetime earnings.