You probably won't be happy with those, especially if going from two to one bulb in the fixture. 24 of 3528 SMD's will be dimmer than the original bulb. I've found that 36 of those SMD LED's on a panel are closer in lumens than 24. 48 chips are more than equivalent in "warm white".
I bought different panels from Chinese E Bay vendors until I arrived at a panel I liked. I then bought them in bulk for replacements. The panels I bought came with adaptors for different fixtures. My 12V system operates at up to 15 V in Winter and I haven't lost a single panel.
An alternative to 3528 SMD's is the newer 5050 SMD. They are brighter with less chips in the same footprint. They also consume a bit more power but still 1/5 of conventional incandescent.