In connection with a mortgage loan on the security of real estate designed and used primarily for residential purposes only, which mortgage loan was acquired pursuant to §§ 58-27-32 to 58-27-40, inclusive, an insurer may lend or invest an amount not exceeding twenty percent of the amount loaned on or invested in such real estate mortgage on the security of a chattel mortgage to be amortized by regular periodic payments within a term of not more than five years, and representing a first and prior lien, except for taxes not then delinquent, on personal property constituting durable equipment owned by the mortgagor and kept and used in the mortgaged premises.
SDCL 58-27-45