[Mr70]

dreemz
I confused you in part with a COPO Chevelle application..
The 1969 Chevelle L78 was built with a 3 core Radiator as std. on the line.
Auto Trans. was Coded BW Part #3020143.
The VO1 upgrade was Coded BR Part #3029205.The BR has a deeper core thickness.

The Manual Trans 1969 L78 Chevelle,was built with a 3 core Radiator std.on the line.
Coded BO Part #3017256.
The VO1 upgrade was coded BQ Part #3019204.The BQ had the advantage in Core Constant displacement.

These & the RPO-VO1 upgrade Radiators were also used in Various other Chevelles for 1969,including air conditioned optioned Chevelles.
When the COPO Chevelle (427 cid) was built,it received the VO1 Heavy Duty BR or BQ upgrade radiator as std. Equipment.
Similar to the Heavy Duty BE & KQ 4:10 Posi Rearend gear,over the Std. 4:10 BV & KK 4:10 Posi.
These exact Radiator Part numbers & Codes were also carried over to the 1970 Chevelle/Monte Carlo applications as well.