This works. Now just need to eliminate the current product from the list.
$relatedImages = get_field('images', $product->ID);
$size = 'related-product-thumbnail';
$relatedThumb = $relatedImages['sizes'][ $size ];
?>
<li>
<a href="<?php echo get_permalink( $product->ID ); ?>" title="<?php echo get_the_title( $product->ID ); ?>">
<span><img src="<?php echo $relatedThumb ?>"></span>
<span class="related-product-title"><?php echo get_the_title( $product->ID ); ?></span></a>
</li>